Cor! Missed this one! Hmm, well on the knowledge front I'd say Evan and Erich. Adler and Plan D are very good as well.
Humour - Les, who reminds me of Dennis Leary, and if you didn't know them better, you'd think the Lanc and C.C's stuff had been worked out as a proper comedy script. Add Skim and Les as a foil for them it's howling at times.
Enjoyable conversation - all the major posters create that, but if I was forced to pick out one, I say Crippen in her heyday was very good at getting that kind of ball rolling.