Hard to overlook the two daily UA nonstops IAH-SJC, but then you have the side question as to whether the departure times are ideal (0925 or 2110) and will work into your schedule. With AA you'd have to connect, though they have 10 flights a day IAH-DFW and 10 flights a day HOU-DFW, and there would also be some US options (5 flights a day IAH-PHX and PHX-SJC, and also some via LAX). Once you're at DFW, AA only has 5 flights a day to SJC, though 10 flights a day to SFO. UA, in comparison, runs 10 flights a day IAH-SFO, so if you can do SFO from IAH that may be the best flight option of all of them if you value your time.

In terms of frequent flyer benefits, you'd earn 11 miles per dollar spent at UA, less taxes, once you hit 1K. At AA, you'd earn 100% flight miles plus 100% bonus miles. Hard to say where you come out better without calculating what you spend on tickets. Upgrades might tilt towards AA as you're not in competition with a UGS-type tier above you.