So which characters were blessed with the greatest bounty of excellent bad guys, and which ones should really be ashamed of themselves for even trying it with their pathetic excuses for villains? The answers may surprise you! But probably not. Onward!
Best
5. The Fantastic Four

Really? Yes, really, but 90% of the reason can be explained with one word, and that word is DOOM. Dr. Doom is the archnemesis of the Fantastic Four and also happens to be the quintessential Marvel, if not the quintessential comic, supervillain. His winning personality and constant attempts at world/galactic/dimensional domination keep the entirety of the Marvel universe, not just the Fantastic Four, on their toes. Add in Galactus, devourer of worlds, and various alien races who got their start with Marvel's first family, and weep anew that the MCU will never get to use most of them in future movies.
Notable Rogues:Doctor Doom, Galactus, Kang the Conqueror, Fing Fang Foom, Kree, Super-Skrull/Skrulls
Grimdark Pick: Besides the Marvel zombies who got their start trying to snack on the FF, you're going to have to go with (who else?) Dr. Doom, especially when he fixates on saving his mother's soul from Hell and creating armor from his loved ones' flesh and so forth.
4. Superman

Actually, Superman has fewer worthy villains than you'd expect from the first superhero ever created, but he has enough to secure himself a place on the list. Especially since he's got Lex Luthor, probably the biggest bad of DC, and tends to be the first to encounter cosmic threats such as Darkseid (the original, non-purple Thanos who will probably now be ironically remembered as a Thanos ripoff).
Notable Rogues:Lex Luthor, General Zod, Cyborg Superman, Bizarro, Brainiac, Metallo, Mr. Mxyzptlk, Lobo, Superboy Prime, Darkseid, Doomsday
Grimdark Pick: Even though Doomsday is basically just Hulk with bone protrusions, the fact that he famously "killed" Superman after beating the crap out of every other hero in Metroooopliiissss makes him the most enduring (maybe only enduring?) grimdark villain in Superman's gallery.
3. Spider-Man

Definitely the best-endowed (heh heh) of all the Marvel solo heroes. Spider-Man has the annoying habit, common to Marvel, of sharing his baddies with his peers (e.g. Kingpin with Daredevil), so that he gets the lion's share while poor other heroes are left with the dregs. And while his villains are numerous and tend to have cool athletic gimmicks in keeping with Spidey's unique acrobatic fighting style, a lot of them are very samey ("The [Animal Name]"), not to mention 99% male, so not quite interesting enough to make it into the top 2. In addition, Marvel has built up Green Goblin as his arch-nemesis over recent years, in no small part due to poor Gwen Stacy, but fuck them because this is my list and Doc Ock is his arch-nemesis, ok.
Notable Rogues:Doctor Octopus/The Sinister Six, Green Goblin, Hobgoblin, Demigoblin, Vulture, Rhino, Scorpion, Mysterio, Black Cat, Jackal, Shocker, Sandman, Electro, Kingpin, Chameleon, Kraven the Hunter, Lizard, Doppelganger, Morbius, Kaine, Tombstone, Venom, Carnage
Grimdark Pick: Carnage, the villain so horrific that he compels Venom to actually team up with his hated crush Spidey, has yet to be used in a Spider-Man movie -- understandably, because he is over-the-top violent and basically a cheaper Joker in a symbiote suit. Still, he's a fan favorite, especially when it comes to Spider-Man's own expanded universe, so expect him to appear in one of the crappy Sony movies in the future regardless of how much he doesn't fit.
2. X-Men

If the question was solely who has the most interesting and well-rounded villains, the X-Men would definitely win the prize -- primarily because most of their villains have become "good guys" and vice versa over the years. A lot of shades of gray here. Not only do they have Magneto, the best comic book villain of all time, they have something actually approaching gender equality with their enemies (as with their heroes), and often fight teams and organizations made up of varied and interesting characters rather than just one supervillain (though they do that plenty, too). Most other comics could only dream of having even one opponent as memorable and exciting as a random X-Men baddie. Truly an embarrassment of riches.
Notable Rogues:Magneto/The Brotherhood of (Evil) Mutants, Mystique, Destiny, Sabretooth, Toad, Juggernaut, Blob, Pyro, Azazel, Mr. Sinister, Omega Red, Mastermind, Emma Frost/The Hellfire Club, Lady Deathstrike, Nimrod, Callisto/The Morlocks, Cassandra Nova, The Shi'ar Empire, Reverend Stryker/The Purifiers, Sauron, The Brood, Apocalypse/The Four Horsemen, Onslaught, Legion, Dark Phoenix, Sentinels, Master Mold, Xorn
Grimdark Pick: The Brood is basically an insect knockoff of the chestbursters from the Aliens franchise, but that makes them no less terrifying or horrible and one of the more memorable threats in an excellently threatening comics universe.
1. Batman

There is no competition here. I'm sorry. No competition at all. The World's Greatest Detective has one of the most extensive rogues' gallery in all of fiction let alone comics, a huge percentage of whom have remained iconic since their introduction, and remains unparalleled in public awareness of his villains. True, a lot of it is because Batman himself has been so hugely popular, with endless TV shows, movies, cartoons, radio shows, and books that brought him and his crazy battles to the fore for 75 years, and maybe a lot of it is Gotham City itself, which is basically a supervillain petri dish that spawns them like coat hangers in a closet. The fact remains that Batman has his own hospital (Arkham Asylum) exclusively devoted to housing the endess entertaining nutjobs that he meets on the daily, and that his iconic villains KEEP SPAWNING, whether it's Harley Quinn from Batman: The Animated Series or Grant Morrison's two dozen new weirdos he wrote a few years ago. It's ridiculous. Also someone needs to tell Batman that whatever he's doing really isn't working, js.
Notable Rogues:Joker (duh), Riddler, Penguin, Two-Face, Catwoman, Mad Hatter, Mr. Freeze, Scarecrow, Clayface, Poison Ivy, Ventriloquist, Ra's al Ghul/The League of Shadows, Talia al Ghul, Bane, Amygdala, Solomon Grundy, Zsasz, Firefly, Man-Bat, Calendar Man, Hush, Dr. Hurt, Black Mask, Lady Shiva, Professor Pyg, Maxie Zeus, Carmine Falcone, Joe Chill, Killer Croc, Red Hood, Harley Quinn
Grimdark Pick:Victor Zsasz, a serial killer who carves a cut into his skin with every kill and is therefore covered head-to-toe in tiny scars, manages to make an impression among a truly memorable bunch.
Honorable mentions:Captain America, simply by virtue of having the entirety of Hydra, A.I.M., Red Skull, and Adolf Hitler himself; Teen Titans, who fight much more interesting bad guys than their grown-up counterparts; and Namor, whose enemies are Everyone Else in the World (especially Mr. Fantastic and Black Panther, exceptions given for Sue Storm and Steve Rogers).
NOW THE WORST, YEAAAA
5. Aquaman

QUICK, name an Aquaman villain. That's right, you can't (Black Manta is a mulligan). It's not really his fault, though: Aquaman suffers the fate of 90% of C-list-and-under superheroes in that he doesn't even have a proper nemesis to call his own. Still, Aquaman's a particularly sad case in that all his "bad guys" are fish-themed and have names like The Malignant Amoeba and The Human Flying Fish (not kidding). Time to go see what the Justice League is up to, tbh.
Who tho?:Black Manta... and like... the Fisherman? The Fisherman is an actual Aquaman villain btw. That's sad.
4. Thor

This one's bad (a) because of Thor's new prominence in the MCU and (b) because everyone thinks of Tom Hiddleston's Loki when they think of Loki. Sorry to break it to you: comics Loki is one of the dullest, most insipid excuses for a supervillain ever to reach nemesis status, and what Kevin Feige and Tom Hiddleston have made out of him is nothing short of a miracle. (AND DON'T MENTION KID LOKI because Kid Loki was made in the past like ten years and he's also not a villain.) Thor's other bad guys range from nobodies to ill-adapted mythological figures and are guaranteed to put you to sleep. Mjolnir deserves better than this.
Who tho?:Loki (only interesting when he had boobs btw), Enchantress, that one elf guy, the other elf guy, Fenrir, glass doors
3. Wonder Woman

Fucking unjust. TRULY fucking unjust. The third of DC's holy trinity, the most famous superheroine by far, champion of bustiers everywhere, and most people on this earth can't name a single Wonder Woman villain. DC's been pushing Ares, as in the Greek god of war, for a while as her nemesis, but the truth is that it's historically been this chick known as Cheetah, who is what she sounds like, a cheetah furry. Which at least helps cement the Wonder Woman comic's status as birthplace of every fetish under the sun.
Who tho?:Cheetah, Ares, Medusa, Hercules, Giganta? for real?
2. Flash

Oh, Flash. Now, Flash's rogues' gallery is interesting because they actually call themselves "The Rogues" and take great meta-esque pride in being his villains, but none of that changes how aggressively stupid they all are. Winner of the coveted stupid prize is his "nemesis," PROFESSOR ZOOM THE REVERSE FLASH, who is characterized by wearing a costume with the exact reverse color scheme as the Flash
Who tho?: Captain Cold and Captain Boomerang, referred to as "Captains Cold and Boomerang"; Mirror Master; Weather Wizard; and ofc Professor Zoom the Reverse Flash (you have to say his whole name every time)
1. Iron Man

That's right. Deal with it, RDJ. The most popular superhero in the world right now has the most godawful pathetic collection of "supervillains" ever inked. Iron Man's bad guys are so bad that not even the best attempts of the movies can make them interesting or memorable; his traditional nemesis, The Mandarin, is such a stupid boring racial caricature that one of the best parts of Iron Man 3 was Ben Kingsley revealing that he had just been playing the role of a stupid boring racial caricature. And who else? Not Whiplash or Iron Monger, that's for sure. Not Crimson Dynamo, cause who the hell is that? Not Justin Hammer, who was only vaguely interesting because he was Sam Rockwell. And not Aldrich Killian, who wasn't even a bad guy in the comics, because no one you know remembers any of those dudes' names. Tony Stark couldn't highfoot it to Avengers Tower to be free of their flop asses quick enough. The situation is so dire that Marvel threw Norman Osborn, aka Green Goblin, into his comics in recent years to give their new flagship character someone, ANYONE, to fight. Perhaps they don't want to acknowledge what we know: Iron Man's worst enemy is Johnny. JOHNNY WALKER. And also himself.
Source: Wikipedia and my all-seeing Eye of AgaMatto
And what do you think of that?