I get to use a lot of different cases, so the fact that I've settled on one, for both my iPad 2 and iPhone 4S is pretty significant. The Zerochroma cases have some nice features that really meet my needs. For starters, they have a nice texture that has just the right balance of smoothness and grip. But the real differentiator is the built in swivel stand that adjusts to just about every position you could want, making them great for airplane meal trays, office desks, nightstands, etc. and they are available in black or white, for iPhone and iPad.
The swivel stand adds surprisingly little bulk to the case, and the iPad 2 version accommodates Apple's own Smart Cover, though you'll probably prefer using the case's built in stand instead of rolling up the cover to use as a stand.