Depends what answer you want:
Person you would bet on to make you the most money over a month: Probably skilled_sox (same for a year I guess too).
Person you'd probably learn the most from: depends on how good you are, but for the players that are already good, I'd say somebody like skates would be a really good person to learn from b/c he seems to approach the game or think about the game in a more unique way than a lot of other top players.  I could possibly see learning a ton from livb, but the only person I know who received coaching from him told me how horrible the experience was (the person isn't necessarily the most objective, but just saying, that's all I have to go on).
Best overall grinder: Players like skilled, croix, rice_stud, skates, bcm, dibasio all come to mind.  I'm mostly talking about the ability to play their A or B game for long periods of time (aka profitable volume).
I'm going to reserve judgement on who I feel is just the absolute best player.  I don't watch the best players enough to really get a feel for who is better than who.  At that, it can be a pretty sensitive subject for many players, as most successful players are young and it wouldn't be in my best interest to specifically talk some players up and maybe not mention others.