This could be a highly debatable topic, with many stipulations involved as to how and why a poster should be included on the list, but as far as charisma, humor, and overall popularity...here what I think is a legit top 5 (in no particular order):
1. Squadfather/Sarcasm/Dave (Getbig.com) No need for any kind of introduction here. Dave seemed to singlehandely create and efficiently use all of the catch-phrases posters use here on a daily basis, as well as being the man who solidified what a true "owning" really was.
2. Jeff McFarland (Muscle Mayhem/Getbig.com) McFarlandPT's precontest thread on mayhem back in '04(??) is to this day the most unique, humerous thread I have ever read. A true journey from off-season to contest with Jeff taking every thing in stride to present a great physique on the day of his contest. No one has yet to have the guts to duplicate it.
3. ForemanRules/Patrick Bateman (MuscularDevelopment.com) A no-bullshit guy that is absolutely full of shit. MD has always been quite boring, but this bro was always willing to throw in an off-the wall claim out there just to get things stirred up. I don't make it to MD much anymore, but this guy is still a regular poster over there to my knowledge.
4. Special Ed/Blockhead (Getbig.com) The ambiguously ghey duo (just playin Block!) Two guys who aren't afraid to throw out conspiracy theories or bullshit that the pros and so-called bbing guru's try to get people to believe. They even had the audacity to start a radio show about it all. Two great poster's as well as hilarious individuals.
5. Vince Goodrum (Every forum) No need for explanation...from another planet
I know this list is going to get razzed on, but when the topic sprang to my mind these were the five that stood out the most.
Apologies to J.Falcone and Mars etc...there were just too many to choose from. The True Adonis, as well as GH15 should also fit onto the list somewhere. Like I said this could be modified in several different ways, but the five that I chose were the first to come mind, therefore I felt they fit properly in the top five.