It's also important to note that Verizon uses the Ultra-High bands which are typically faster,
However, they don't travel as far ... This makes it very limited and expensive for them to get the same coverages ...
T-Mobile (and what's left of Sprint) and AT&T use mostly Low and Mid band right now ...
There's very little chance that T-Mobile/AT&T will use the Ultra-Bands any time soon (from what I can see)
You can look up a phone's individual specs to see which bands it uses, and then reference the link I posted above ...