While it wasn't the best device, last year's ZTE Axon Pro was a big step up for a company that was mainly known for making cheap phones for prepaid carriers. The price has come down in recent months, and now B&H has it on sale for $299.99 ($50 off) with some extras. It's still pretty solid for that price.
The Axon Pro has a Snapdragon 810, 64GB of storage, 4GB of RAM, and a 5.5-inch 1440p LCD. The design is a bit unusual with all the little triangular cutouts around the speaker and cameras, but at least it doesn't look boring. When you buy the Axon Pro from B&H, you get a $75 gift card to spend on anything you like, as well as a clear case for the Axon with an included screen protector.
This is a GSM/LTE unlocked phone that should work on any compatible network, including T-Mobile with band 12. All three colors of the Axon Pro are included in the deal, but the gold one is the only $299 option. The others are a few bucks more. You still get the freebies with them, though.