1. LG Nexus 4 - your best best option. Great screen, buttery smooth UI which is smoother than SGS3 and HTC One X and the software is excellent. No microSD.
2. Samsung Galaxy S3 - your next best option. Extremely smooth, excellent software and no lag, no bugs. Has microSD.
3. HTC One X - arguably the best screen. Not as smooth and has some bugs and hiccups which can get very annoying. No microSD
4. LG Optimus G - great screen. Smoother than HTC One X but software is bad. Has microSD.
Sony Xperia (heard it's very crap because of bugs and software updates are non-existent after ICS). No microSD and the camera is crap for the amount of MP it offers. Actually one of the worst cameras I've used on a phone.