Which current Verizon phones will work on T-Mobile

[AC Question]

this is a little convoluted but I'm thinking of buying a moto X and switching to verizon.

Since I won't have a need for a phone, I was thinking of using the switching discount to buy a phone and give it to my girlfriend.

She's on T-Mobile... hence my question wondering what phone I could buy from verizon at a discount to give her on T-Mobile.

thanks!