thejuice6 definitely
schwarze definitely (the WISC alone is an enormous undertaking)
jfranco77; I've only played a few of his themes, but Favorite Player is a gem, and he's just generally on top of things
I'll second the props for fk6 and finn2030; both are great theme commissioners.
And crazystengel, thanks for the recognition; your themes are also fun to play, you stay on top of stuff and don't make things any harder than they have to be.
The commissioners who really bug me, and whose themes I readily avoid, are those who don't do the work and/or don't police their own rules. If your theme has ANY roster restrictions on it, please be prepared to check EVERY roster carefully. Mistakes happen a lot, by commission and omission. Just as an example, in thejuice6's current tourney, round 3, we're down to a group of very experienced owners. All of these guys are HOFs who play frequently and know what they are doing. And yet about 10% of the submitted rosters needed correction. No one was trying to cheat, I'm 100% confident of that. But mistakes happen. You have to check.