If you don't mind being throttled, why not pick T-Mobile and save a little money?
Your mileage may vary though. It is pretty good in cities. Do you travel out in the middle of nowhere much? T-Mobile might not be the best for you. When I think of satellite phones, I imagine being in a situation that would require me to call for rescue.
I quoted the $70+ figure because you use 3 - 4 GB data per month. You will still keep unlimited data without throttling.