HTC One X

I can't say for sure, but there definitely are two versions of this phone. One is unlocked and has a bigger, but not necessarily faster processor. It just uses up more battery.

Also, my last phone was an unlocked Galaxy S 4g I put on T-mobile. After just having got the ATT One X, I cannot stress how much faster the LTE is. It is faster than the WiFi in office or apartment. I def liked T-mo for price and freedom but, damn, this phone is fast now.