I use Virgin mobile. If you're willing to deal with their buggy piece of shit phones, then don't say I didn't warn ya!
Seriously, whatever phone brand you buy, it'll have Virgin's modified OS on it. My last phone had about 6 easily reproducible bugs on it and my current one has several as well.
When I send a text message, I can't just end/close my phone or it'll hard freeze. I have to remove the battery and start it up. If it was previously on silence/vibrate, it vibrates THE WHOLE TIME THE PHONE STARTS UP.
As for service, I've always had the same issue. When I make or receive a call, it's broken up digitally. If I hang up and call back, it's clear as day. It's like it NEVER works the first phone call out. This has happened across multiple phones as I have been with them for years now.
Don't expect firmware updates. Don't expect sim cards (unless you get a smartphone and get your own miniSD card. Don't expect a lot from them.
But hey, the price is cheap, right?
Lastly, stick with the better brands. Their modified Kyocera phones are the worst. I currently have a not-as-buggy Samsung.