The best are: Shep, Segunda, Mozza, AndreBarker, CP, HenryHill.
Most of the rest are below/average but I would say: Samoon, Cliffy Byro and the Lexarist are the more intellectually retarted members of the forum. Reading one of their posts genuinely make you stupider. As for worst overall, if RKO Peep and andersonasshole900 were banned this forum would improve considerably.
Coming from someone with bad spelling.
There is no best as such but the worst I've seen is Trouble Trouble.