Alstein covered most of the games I would have picked outside of joke answers like the GBA versions of MKT or Tekken, or the DOS or C64 versions of SF2. The PSX vet of KoF95 is bad in a really funny way. It more or less works... except that guard cancels cost 0 meter. Oops!to you, what is the worst console port of a fighting game? and what's the best?
Best: I'll throw in Namco's ports of Soul Calibur and Tekken Tag Tournament. The graphical upgrades at the time were insane and SC is one of the first 3D games I remember that doesn't look awful today (SC's strong art style is a huge assist there). And for SC1, there's also all of the extra content that they added.
VF4:Evo should be mentioned again and again in this regard, because that port was insanely good (even if it didn't look as good as the arcade version).