The Sony supports more 3G and 4G bands. I don't think the ZTE, even its LTE variant, will support LTE from AT&T or T-Mobile. The Sony C6806 and C6806 GPe will work on every band that T-Mobile currently uses.
Sony Z Ultra C6806 Google Play Edition (GPE) on T-Mobile $30 prepaid; Galaxy Note 1 (T879 T-Mobile pentaband) / Paranoid Android 4.1.2
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