Best unlocked iPhone plan advise?

I have a Iphone 4 unlocked and I wanted to know what plan should I get? I mean since it is a GSM phone it only can use ATT and Tmobile. Other prepaid companys like straight talk, att gophone, ect work with this. So my question would be what service is the best and cheapest. I'm searching for the best coverage and data plan.

Tmobile has unlimited text and web with 100 minutes of talk on monthly 4g for 30$ a month

I've used Straight Talk for the iPhone and it was great: Unlimited data, talk and text. Everything cost about $45/month. Straight Talk is what is called an MVNO (Mobile Virtual Network Operator) that uses AT&T's network, so you get the same coverage as AT&T. However the data speed you will get will be at 3G only - still not too shabby for $45/month. You can use data with the GoPhone plan, but the last time I checked Straight Talk was cheaper.

You can check this site for configuring your iPhone APN with Straight Talk:

http://www.unlockit.co.nz/unlockit/

… And this one for the MMS data settings on your iPhone

http://www.howardforums.com/showthread.php/1754006-I-enabled-MMS-without-Jailbreaking-Iphone-4S

I recommend Simple Mobile's $40/month plan. Prepaid, no contract, and you get coverage across the nation on T-Mobile's network. Plan includes unlimited nationwide minutes, unlimited global text, and (supposedly) unlimited Web. First 250MB of web usage in a billing month are up to 4G speeds, beyond which the speed will be throttled down. T-Mobile is doing a re-farm of their networks for 3G/4G iPhone support across all major metropolitan areas, so if you live in a big city, you should be able to take advantage of the 4G (and 3G) speeds.