I am digging the Diztronic matte TPU. It feels good, after the powdery stuff wears off in a few days and the buttons work well.
I have the Case-Mate Hula bumper. It's of good quality and the buttons work well, but the abrupt fall off, on the back, feels weird and I don't like it.
I also have the Incipio Octane-Translucent Smoke and the DualPro. I have not used them much, but both are good quality, fit well and the buttons work well. They are virtually the same size, so if you want a bit more protection, go for the Dualpro and don't worry about it being larger than the Octane. I got the direct from Incipio web site at about half of what amazon wants, because I chose cases for the Style, which is the same phone, with the European modem.
ETA: I've been using the Dualpro, today. It feels good. The back is soft touch matte.
The Octane has a hard back that is frosted, has decent texture and is not slippery at all.
ETA 2: I've been using the Case Mate Hula bumper the last couple weeks. While I still don't care for the abrupt fall off on the back of the phone, I like using it. The low profile makes it easier for pocket carry, but still provides decent edge protection and grip.