[Q] best model of the note 4 to buy? topic

I had a galaxy note 3 and really enjoyed the s-pen, so I decided I'm going to take some tax money and trade in my current phone for a note 4. I want to buy one that the boot loader is unlocked (would like root, custom recovery) and would also need a phone that can get LTE on at&ts network. Would an unlocked T-Mobile phone do this for me? (I'm actually on cricket if that matters). I heard T-Mobile doesn't lock the boot loader like at&t does.