What smartphone/android phone should I get??? iPhone 4, Samsung Captivate, HTC Aria, Blackberry Torch.?

I'm recently eligible to resign a new 2 year contract through AT&T which means I get a new phone at a reasonable price. I want a cool phone, something I'll love, and won't mind using until I'm due for another upgrade in 2 years. I can't decide on what phone I should go with, they all look so amazing. I've narrowed it down to the iPhone 4, the Samsung Captivate, the HTC Aria, and, when it comes out in a couple of weeks, the Blackberry Torch. Any information that would help me choose would be fantastic. Thanks.