Is as close as can be? I was thinking about it, from 1-10 there are differences but not much. I mean look at sindel and kabal, they differ like 8 places but still its not a bad matchup.
If you mean fighters in general, there are a few extremely balanced fighters. I believe the balance in the Guilty Gear series is supposed to be quite good.
There are no MK games as balanced as UMK3.
You can use a lot of characters in UMK3 even in high level play. I think Cyrax and Sheeva are the only ones I haven't seen played well in high level play.
ol: