I'm very satisfied with T-Mobile's HSPA+. When T-Mobile does deploy LTE it will run on a newer, faster version of LTE technology. They'll have the best LTE network available. VZW will be heavily invested in already outdated technology. VZW is just trying to be the first and largest network, mostly for advertising purposes. To them, LTE was 'good enough'. T-Mobile (and other carriers around the world) correctly determined LTE wasn't quite ready and waited a bit for it to mature.
Registered Linux user #266531 Android since v1.0