Purchasing an iphone, which prepaid is better? ATT or Tmobile? 2G or 3G?

[plaguepoop]

Ive currently found a 2g iphone for about 100 bucks, and I want to use this phone as a backup phone. I will definitely not be getting any contracts.


1. Is there any advantage to getting a 3g or 3gs over a 2g? My guess is no as the data on prepaid wont really take advantage of the 3g or 3gs, but Id like someones input.

2. Which of the two carriers are better (regardless of coverage)?
Also, if I purchase minutes, is there an expiration period (Valid for only 30 days or something)? Or will my minutes last until I use them all?

3. Around how much am I looking to spend per month? Im guessing this depends greatly on whether or not minutes dont expire every month. Does the 20 dollars for 100mb have an expiration time as well?

did i post in the wrong section?..

[funcritter]

I've used both phones with an AT&T GoPhone plan and have no problems with either one. 3G will work great with AT&Ts 3G service on prepaid as well. The data plans are expensive though as you know.

I have noticed that using a GoPhone sim in my iPhone tends to make the battery drain faster. I haven't figured out why.

[plaguepoop]

so would you choose att prepaid plans vs tmobile plans? whats the difference in price?