Both AT&T and Verizon have LTE coverage in LA. However, AT&T's coverage in CA only covers LA, San Diego, and San Francisco. Verizon's coverage in CA covers much more such as Santa Barbara, Bakersfield, San Luis Obispo, Fresno, Monterey, San Jose, etc... So if you plan on traveling around the state, Verizon would be the better option. AT&T's LTE is significantly faster in major areas, due to the far less number of users, so if you are primarily going to use it in LA, it probably will be the better option for the near future.