I couldn't agree more. I recognise many of the names mentioned by earlier posters and would probably vote for them in any "top poster" poll, but the apparently simple question "Who are the best SB posters?" is fraught with subjectivity. For starters, the posters likeliest to win the most votes will be the generalists, who hop confidently from one SB forum to another, dispensing their wit, wisdom and occasional expertise everywhere. The specialists who stick to a handful of SB forums, spending hours of their spare time analysing in depth and solving other people's problems may be relatively unacknowledged, but they no less form the "critical mass" of SB than the generalists do. It all depends what you want out of SB, humour, expertise, companionship, human kindness, a sympathetic ear, a shoulder to cry on, a joy to be shared, whatever. You will seldom find one individual, let alone one single SB forum, where you will find all that in equal measure.
AndrewA makes a very good point about the best SB poster of the moment often being a new poster who asks a question which every SB regular has failed to ask until now but which matches exactly another member's knowledge and expertise. I mainly inhabit the snorkelling/freediving forum because I don't scuba-dive. I'm always delighted when a "newbie" comes along with a question about cold-water snorkelling, because that's my area of experience.
Final point: any "Who's the best SB poster?" poll may only tell us who is the most popular poster, who may, say, tell the best jokes or express themselves well, but not actually solve anybody else's diving-related problems. I think you'll get a clearer answer by finding out which SB poster has the highest percentage of "thanks" per posting. Yes, I do know enough Maths to be aware that new posters could get "thanks" for their first question and so get 100%, but it's not beyond the wit of man (or woman) to come up with some formula that measures posters' "usefulness", as recorded by the "Thanks" button, as well as "popularity".