I never thought Altered Beast looked Arcade in quality. And seeing it in motion sucked away any interest I had in the Genesis. The TG16 had all these colorful games and when Bonk's Adventure came out I knew I had to own that system. Of course as a "gamer" that had to play everything, eventually I owned both and had plenty of fun with both systems.
Altered Beast on the Sega Genesis looks worlds better than the PC Engine version, and it does look fairly close to the arcade version. It's not flawless, but it's certainly a solid arcade port by the standards of the time.