Still fire Marvel vs Capcom 2 on my Dreamcast occasionally. The epitome of the vs games imo. Also Guilty Gear, Blaze Blue, Soul Calibur, and Streetfighter 4(which apparently is a great party game.) Not to mention the KoF '95/2000 and Samurai Spirits II games for the Neo Geo, but I always feel nervous playing it because it's like a rare gem. Someday I'll get my hands on a copy of Last Blade II AES cartridge.