Best: Blue Heaven, Mystic Realm, an old Green Hill Zone for 1094, Sonic Rider, more that I forgot Worst: Sonic Quest, the special stages, more that I forgot
My favorite mods are SA2B, STH360, or any other related-to-other-sonic-games-made-from-sega. My favorite charachter wads would be Silver.wad and a Sonic next gen wad. And my favorite hangout wad would be house20, or house22. (New versions coming out ALL the time.)
P.S. Did you ask me what games I find WORST? Well, I don't find barely anything totaly BAD.