What one do you have and what do you think of the provider?

I use At&t's "Go phone" program for my business cell phone. It is cool, free long distance, free roaming, free nights and weekends, and 600 anytime minutes for $50 a month. It is not as good a deal as my contracted plan but I like it because I can shit can it anytime I want.

T-Mobile pre-paid GSM. One year expiration date for purchased airtime, ten cents a minute for any phonecall I place or receive. Unlimited incoming text messages and e-mail. Text messages can be sent to the phone via another cellphone, as e-mail, or via MS Messenger. Ten cents per outgoing text message or e-mail. Voicemail, three-way calling, caller ID.
All digital, all GSM-encrypted....all rural areas are dead zones.

I have Cingular prepaid.  Kind of a ghetto phone but it works in most of the areas I usually go.  Can buy minutes online instead of having to go to the store to buy a card.