Without a doubt KoF '97. On top of great graphics & storyline + multiple endings, one gets the game most tailored to combo masters: crazy juggles (you just have to see some of the sick shit possible in this game), great & comboable supers, moves that don't connect in later installments and the general ability to turn almost any attack into something more. Keeping with the KoF tradition it's also got 100% combos (laugh in delight as your friends die from only one fatal mistake). It's got a lot of learning material in the game, with some alternate versions of characters (including bosses) bringing the total to 38, or 39 if you have access to the dip swtich settings. The character theme songs are extremely well done: they're wonderful, but of the stage music tracks, only the three boss levels have real music; the rest are just sad. Continue-free survivor mode is also a highly addicting factor.
All in all, you can't go wrong with this game. It has the combo system I would venture to say you're after, and one of the highest readings on the Digital Crack Scale. You won't be disappointed with it! provided you don't already have it. I do have one for sale, but that wasn't why I posted all this. The game is a real masterpiece and deserves all its good press.
Hope this answers the question for you.