Another point is AT&T is 2GB of 3G data. Time will tell what AT&T charges for LTE when it deploys.
Another point is ATT's minutes roll over, Sprints don't. Another point is Sprint offers 2 forms of FREE turn by turn navigation, ATT offers none. Another point is Sprint forces you to pay for unlimited texting by including it in the price, whereas ATT doesnt (and anyone with a droid or iPhone that's using the carriers texting method is using an inferior app).
For me to get an EVO, it would cost me 79 a month plus all the stupid taxes. For me to get the iPhone 4 its going to cost me about 60 bucks plus stupid taxes.