i haven't played Marvel Heroes vs. Street Fighter, so i can't say anything about Cyber Akuma. i only played X-Men vs. Street Fighter briefly (rented it), but i remember that huge-ass drill that Apocolypse had was cheap as hell if you didn't jump out of the way. As for the Marvel vs. Capcom games, Onslaught was a pretty cool fusion between Magneto and Professor X, and it was fun being able to play as him against a friend just so you could hide off-screen. >=P i'm not very knowledgeable about Marvel/Capcom history, so Abyss kinda seemed like a random boss character to me, although he DID have 3 forms, and he WAS rather difficult at times. so, i'd say either Onslaught or Abyss.