I haven't heard anything about them freezing, but I've never used one. They have the same processor as the Galaxy S 3 American version (Qualcomm snapdragon S4) so they should be pretty snappy.
And as far as which one: The 920 is big, as in heavy, but sturdy. Also it has a great camera and screen.
The HTC one 8X is lighter and smaller, and has some good features too. They both have the same processor and 1GB of RAM. So its more of a personal preference.