I use an ATT Go-Phone for Baja, excellent coverage, low rates. I load the phone with $50/yr, rarely use up the minutes. I don't use my phone much when in Baja, but I have been impressed with the coverage when I do need to use it.
Verizon coverage in Baja is almost non-existant.
Pre paid means no surprise phone bills when I get home, and if I lose the phone or it gets stolen it's not the end of the world.