AT&T may get a GSM version of it next year I believe. The company just got the Bold. I doubt they would try to get another phone to bump their new flagship phone.
Honestly, I would prefer the Bold over the Storm. But that is only my preference. I've had the opportunity to play with both as my co-worker has a Bold. It might just be a learning curve for me right now since I'm i\used to having an actual keyboard to type on. However, the fun factor on the Storm is great.