Personally, Rockman 8 is my favorite, if only because it has my favorite Robot Master in it (Astroman with Astro Crash FTW). Yeah, the voice acting wasn't the best, but then again, voice acting on Playstation games were kinda awkward anyway, in my opinion. Wait, I think I said another reason (beyond not being 8-bit) reason right there about 8. It went from a Nintendo system to a Sony system.
Rockman 7, not too sure. Obviously, not 8-bit. When I first played it, I plowed right through it, now I go back and play it, and I can't even get to the first checkpoint. That has no relevance, but I felt like putting out there (My skills are degrading!!

).
Rockman and Forte, never actually played it, so I can't place an opinion on it.