Depending on how much data you use, GOOGLE-FI can be a great option.
They combine T-Mobile, Sprint and US Cellular domesticly They make one network with dynamic switching between the 3...net results is very good coverage similar to Verizon/AT&T, but lower cost, and great customer service.
$20 a month, unlimited talk and text, then $10 a gig for the first 6 gigs if data, free after that...
International data is the same price, and coverage is very good.