It looks like I will be relocating to London from Washington, DC and my new position will require a fair bit of travel weekly within Europe and twice a month to the USA (east and west coast).

I expect that the company will pay for refundable Y but not C or F.

I am currently DL Silver Medallion (not much travel in my current job) and am wondering what the best option is for me based in London. I am assuming that I will bank well over 100,000 miles a year. What are the advantages of BA-EC over UA and Star Alliance or sticking with DL and AF. I am cognizant that travel on one alliance member is not the same as flying on your "regular" carrier in terms of upgrades, etc.

I understand that not all BA fares qualify for tier points, but assume that refundable Y tickets do. How does the Star Alliance stack up... I know that UA is fairly liberal on the upgrades when you get to 1k.

Can someone advise as to the considerations that any of you think relevant in deciding which program to settle on as I settle in London.

Thanks in advance for your advice...