T-mo's web site has all the options listed. How much web surfing do you want to do? Do you want to do any texting? Do you want to stay with the prepaid model, or do you want to do a contract/postpaid model?
Prepaid/no contract plan info:
No contract phone info:
I just read an article that talks about how people are going to prepaid overall for all carriers, for a number of reasons. To me, it makes sense; I have zero reason to be held to a contract. But, if you want a contract/postpaid setup, t-mo offers those as well:
A very popular plan is the new-activations-only, web- or walmart-only $30/month plan that gives unlimited web (first 5GB at 4G speeds), unlimited text, and 100 minutes voice. Yes, it's new activations only, but if you poke around here you can find out how people have moved their numbers over to that plan once activated.
You buy your own phone or bring your own phone to the prepaid plans. I think t-mo's web prices are high; find a phone you like anywhere, new or used, and bring it to the party. For example, t-mo sells the Samsung Exhibit II for $250, while walmart and amazon have it for $190. Used, it's about $100. That's just one example (and for $100, it's a fine phone).
If 100 minutes of voice isn't enough, you can simply pay t-mo's ten cents/minute overage as you use them, or you can use some VoIP mechanism to make calls using your huge data allowance. I use Vonage Mobile.