Currently, T-6 is more convenient for American Eagle gates (remote gates 60 A-J) and Legacy US flights. ThreeJulietTango states at this time "Mainline LUS flights are identifiable by flight numbers in the 400-899 and 1675-2174 ranges." (Unfortunately that also means LUS narrowbodies with no power or IFE.)
LAA mostly depart T-4 and the four TBIT gates.
They're all connected airside now, other than the Eaglevterminal, which is only accessible via airside shuttle bus.