I'm playing the KOF games. Moreso, KOF 98 aka KOF Dream match and KOF Evolution.
Both games and the others in the series are really nice, but the bosses I have fought, in both KOF 98 and KOF Evolution, are cheap as heck, even on easy mode.
After playing a few KOF games, I kinda understand why people highly rate KOF 98, over the later entries.
The dreamcast versions of KOF, have 3d backgrounds and objects. But I have to admit, the two european clock tower stages in KOF Evolution, with the wooden people statues, are amazing too look at. Like holy crap, those two stages are lovely. Check them out if you ever have time. I'll check out the other classic KOF games, as soon as I can.