To be totally honest, my favorite fighting game series is Melty Blood, specifically the newest incarnation, Act Cadenza. Oddly enough, it trumps the other fighters I play (which are, I assure you, numerous) not for its intricate combo system or the incredible variety in characters, but for it's storyline and characters. It's based on a japanese visual novel called Tsukihime, which I have played rather extensively, so you know that it has a good story, as it is based off of, essentially, a book, which has no other means of entertainment.
Story aside, though, the game is really fast-paced, and the system allows for huge, elaborate combos. Every character is hugely different from each other, even the clones. The few clones they do have are treated in much the same way as Luigi or Falco; at first glance, they may look similar, but their playstyles are totally different from their counterparts (with the possible exception of Nanaya Shiki <_<) No two characters play even remotely similar to each other, and most characters have some sort of gimmick you need to master to play them effectively. Arcueid has her wallbounces and relaunches, Ciel has her incredibly diverse okizeme game, Akiha has high/lows, etc.
The game *seems* to be fairly balanced, though that could have to do with its relative lack of popularity in America. Well, not relative, I suppose, nobody really plays it in America. The tier lists from the early days of Act Cadenza looked entirely different from the current lists. Only a select few characters stayed at their ranks, while the rest pretty much just flipped around. Kouma used to be considered the worst non-joke character in the game, but now, he's S tier. Red Acrueid used to be considered the best in the game, but now she's mid-tier. Come to think of it, that doesn't really suggest balance, but you don't see a character division like that in SSBM or MvC2; everyone plays the character they like the most, and they always have a good chance of victory.
I dunno, I guess you could say that the main reason why I like Melty Blood more than other games is because I'm a fan of the game it's based on, but even without that, it's an incredibly solid game, especially considering that it's basically a fan-made game for all intents and purposes, and is definitely worth checking out for any fans of 2d fighters.
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Whee! Another novel-esque post from Dreadlord-san!