What's the best way to test out the service of ATT and T-Mobile without actually switching to them? I have a REALLY good deal with Verizon and don't want to give that up until its time to switch but I just moved to a new state and the speed/coverage isn't great.  I am curious about T-Mobile and ATT, I'd like to test out their coverage and do a couple speed tests at work and home and in between.  I think the best way would be via a pre paid sim card but I wanted to check to make sure thats the best way to do this.
