High Fantasy: The best genre for all types of roleplayers. As rookies will have more room to breathe without being bogged down by strict logic and rules. (Think good Sci-Fi.) Writers have more room to be creative and worldbuild. And even lazy roleplayers will have less excuses for why they can't contribute. (When basically everything is on the table.) And those who are good at it, can make the very best out of the everything offered to them. Etc etc.
 
(Though really, you'd be hard pressed to find a genre that I can't enjoy.)

So what do I like to see in RP's I'm in?

Group RP's that let your decisions affect your own character and the plot 
in meaningful ways. And 1x1's where both parties have free reign to actively contribute to the plot.

Sure, it's fairly basic building blocks for collabrative storytelling. But that doesn't mean you'll always get it. So it feels nice to get it when you do.