For caparison, Verizon and AT&T have it at 22 GB while Sprint has it at 23 GB. I also heard a rumor that Verizon is starting a campaign to get their biggest unlimited data consumers off their network. Their network is obviously hurting big time when they re-introduced unlimited data plans. Will see if this raise from T-Mobile hurts the network but I don't really see it happening.
http://www.tmonews.com/2017/09/t-mobile-may-increase-deprioritization-threshold-50gb/
http://www.tmonews.com/2017/09/t-mobile-may-increase-deprioritization-threshold-50gb/