I have people who swear by Sprint and other people who have to have land lines specifically because Sprint doesn’t work in their homes (which seems to make the value moot).
Almost all phones now are world phones though, so it’s not like the old days where you couldn’t travel with a CDMA phone. But the bigger issue is that if you get a carrier locked phone then you will not be able to put a new SIM card in it once you leave the country. I keep an old unlocked iphone around for when I travel internationally.