-Mortal Kombat gets by on its shock value. I never felt it had balanced fighting mechanics.
-Virtua Fighter has bland and forgettable characters.
-Killer Instinct was all graphics and flash.
-Super Smash Bros. is too chaotic with four players, power-ups, giant hands, and such.
-Dead or Alive is okay. A bit bland and simplistic, though.
-Marvel vs. Capcom has serious balance issues.
-King of Fighters is a poor mans Street Fighter (along with 99% of SNK's fighters).
For me, it comes down to Soul Calibur, Tekken, and Street Fighter. And even though I'm having a hate/hate relationship with Capcom right now, Street Fighter takes it.