I really like my iPhone SE. Not crazy tablet sized like the 6 and 7, but it has the same guts as the 6. Haven't looked into androids since getting my first iPhone years back. Back then the build quality of even the best androids just wasn't up to par, and I've really come to dig the Apple simplicity when it comes to a phone.

As for a carrier, check out r/nocontract. I've just switched off of a major carrier after doing some reading there, and it looks like my bill will be cut in half or better. YMMV, but it seems like the hive mind agrees that buying your phone outright and getting service through a carrier that uses one of the major carriers networks (boost for example is the AT&T network, I beleive) is the way to go.