Lots of very good posters and I enjoy the opinions of many. To many names to really name.
My top four favourites are
TMV, NyQuil, Minister of Offense and trentmccleary (I don't agree with a bunch of stuff trent writes and it's infuriating at times arguing with him but the dude speaks my language with backing up his opinion with solid statistical facts)
I'd like to nominate Dr.Sens(e) for Most Underrated Poster and Best Poster Avatar. I find his posts and his opinions are very often very well thought out and written, he's a enrichment to this board. Not to take away from other very knowledgeable posters that have been nominated by several posters already, but I didn't see him mentioned so I wanted to add.
Only a couple of endorsements to make... not really nominations, per se, because they've already been nominated, but MaindotC, zekeA and mianjo deserve their nominations for dedication. Phenomenal efforts this year.
Most improved should definitely go to OmniSens... and if you don't believe it, read some of his earlier posts in the GDT making thread.
Nicest poster should definitely go to Liliaceae. Haven't had too many interactions with her, but in my time on these boards I haven't seen her say a single bad thing about anyone at all. That said, I appreciate the votes for me in this category.
Lastly, I love that trentmccleary and The Fuhr back up their arguments with solid facts, and both deserve noms for best poster, but my support for this one goes to a bit of a darkhorse, The Waffler. Often either thought-provoking or funny, but never too over-the-top. Has a sense of humour and doesn't bleed of homerism. If I could pick one poster to represent the fanbase as a whole, it'd be Waffles.
Not to discount anyone who's been nominated so far, of course, this board wouldn't be the awesome welcoming place it is without the great people that frequent it.