I have been United 1K for 5+ years, moving to UK from US in a week and will be there for the foreseeable future.
My annual travel is expected to be:
1) 3x return LHR-SFO-NYC-LHR in Business.
2) 1x return LHR - DEL - LHR in Business or Economy.
3) 2-3 return trips within Europe.

Given the above,
1) which airline program should I switch to?
2) If the answer is BA, should I status match to AA -> BA or go directly with BA?