Unless there is a big price difference, I will take the UA flight and have the bags check-thru.
You can also ask if UA can check you in to the BR flight at SFO. They may not do it but it wouldn't hurt to ask.
Most of that extra hour you'll gain from taking the early VX flight will be lost waiting for your luggage to come out at LAX.
If you have BR boarding pass and bags check-thru, you can transfer from T7 to TBIT without leaving security. That's way better than flying VX and having to retrieve your checked luggage. Security line at TBIT at 10 PM is LONG... peak departure hours for multiple flights by CX, CI, BR, QF, and VA.