He's not going to find a program with better redemption options than UA. He's also going to have to connect to fly international out of SFO on any other US carrier (LAX/DFW/ORD on AA, PHX/CLT on US, SLC/ATL/DTW on DL). There's a reason UA has so many high level elites at SFO - it's not the only game in town, but it has big advantages over all the others.

But if he travels quite a bit to Asia, joining the AA program and flying OW partner CX might be a reasonable option. Likewise BA to Europe.