I used to have sprint, then switched to verizon.
Gotta keep in mind that these more expensive plans from the big carriers like ATT, sprint, verizon, etc all pretty much give you free phones every two years. In reality, you are just paying for the phone with the added cost of the plan.
My choice to go verizon was more about service where I live, and phone selection. So my $150/mo plan is really more like $100 if you factor in that I got two $600 smartphones for free.
I really couldnt find an appreciable difference in any of the plans/carriers I was shopping. Straight talk, virgin, revel, ATT, verizon, T-mobil, etc. Some were a tad cheaper, some a tad more.....but not huge differences with all things considered. IMO, verizon has the best selection of android phones, and they certainly have the best coverage in my area.