I have Virgin Mobile, and previously had Boost, and they both use the Sprint networks, and it truly sucks. I always end up putting my cell phone on airplane mode while at work. The busier the park is, the more quickly the battery drains, and the harder it is for me to do things like send text messages, and forget any kind of internet connection, I usually lose it as soon as I get into the parking garage. Oddly enough, I usually manage to pick up Transformers wi-fi signal. In my department's office, I usually have to walk up to a window, or go outside in the back, to get a text to send, can't make a phone call at all inside.
I have no idea who to switch too, because I will NOT go for a contract again, pre-pay is the way to go, and Verizon and ATT have pretty high-priced pre-pay. I'll wait for my phone to quit working before I switch.
At Disney, I have no problems with Virgin, but since I'm rarely there, it does me no good at all.