So far I'm not impressed with T-mobile's coverage. It's been about as bad, and sometimes worse than Virgin mobile, both around my local area and on a trip to rural West Virginia (both had almost no coverage on most places on the trip, and both are hit or miss around town). I wonder if T-Mobile's LTE would have better coverage in my local area (which does have T-mobile LTE: DC Metro area): My phone only has HPSA+.
I do like the T-mobile voice/text via WiFi feature, especially since neither TM or VM work well, if at all, in my house. Too bad voice over WiFi still uses your voice minutes.
Other than the lousy connectivity of T-mobile, the LG Optimus L9 is exactly what the Triumph should be: Everything works great so far (though it is missing the notification LED). GPS is fast, touch is very responsive and reliable, the OS is fast and responsive, etc.
Other people's Verizon phones (though they were just phones, not smart phones) worked great on the trip to rural WV. Of course, Verizon is about 3 times the price of VM/TM prepaid if you want a reasonable amount of data on a smartphone.