I just switched to TMo. Two unlimited data lines, each includes 5GB of tethering and Rhapsody subscription (normally $4.99/mo each), plus two 2.5GB/mo lines (1GB in 2016), plus a 5GB/mo cellular iPad plan. All lines include unlimited talk and text. All for $150/mo with my 15% discount. Music streaming from popular services that don't count against your data is a great feature.
Speed in my house is ~40mbps, compared to the measly 4-8 I was getting with ATT. From what I've seen, in areas with good reception, speed is superior to both ATT and Verizon around NJ and NYC. What I do notice is coverage when inside a store is not as good as ATT.
I'm very happy with the move. I gave up perhaps a bit of coverage for a lot more. I was paying more on ATT with just two smartphones and two dumb phones, without any of the extras like tethering.