I'd like to stay on AA so I can use VIPs to upgrade to F. He ended up recommended DFW over LAX, though: DFW-LHR on AA, then LHR-BUD with 1:40 in LHR, which still sounds a little tight for the T3-T5 shuffle.

Separately, on a BRU trip, I have an award booked LAX-LHR-BRU all on BA, with outbound in J and return in F, but am toying with the idea of switching LAX-LHR to AA in F, giving me the better AA F seat over the BA J seat, saving a T4-TBIT change at LAX with extra security screen, but costing a T3-T5 change at LHR with security screens, busses, etc., plus a few extra miles.