I am using Samsung Galaxy Note II..We generally get better apps here in comparison to any other model..
I currently use a SG S2. Stuck in quite a long contract (I didn't want to wait for an S3, even though it would have been just a week), but the fact is it's a great phone. I don't play any intensive games on it, so the size (screen) and CPU/GPU are enough. Anyway, I have a quadcore tablet as well. To be honest, I'm more interested in technology such as Google Glass. It could largely make a mobile something that remains in your pocket, once the tech is refined a bit more, in terms of style/bulk. (That won't be easy, though.)