I think that most or all of the GSM-family carriers in the US will accept most anything (though the details of exactly what data rates and things will or won’t work based on frequencies supported can be a bit alphabet-soup at times); but they may charge you exactly the same as if you were receiving a handset subsidy.
Verizon is notoriously nasty about non-blessed devices; and only a minority of devices on their network even have a user-swappable SIM (or equivalent, the semi-convergence of the GSM and CDMA camps in LTE-land gets pretty baffling) that lets you try, rather than having to call the carrier for provisioning and get shot down. I’m not sure about Sprint. Architecturally, they are in the VZ camp; but they are smaller and hungrier, and might be more reasonable.
(One note, from personal experience: Tracphone is a fairly good deal if you just need a super-minimal number of minutes, want to keep a phone number, and need the portability of a cell (so, say, porting it to a SIP provider isn’t an option); but their ‘SIM cards’, despite looking like they should, don’t work in any non-tracphone handset, nor do non-tracphone SIMs work in their handsets. I don’t know the details of how the locking is done, or whether anybody has hacked around it; but don’t expect it to just work, because it won’t.)
