You seem to have identified the two best options given your situation. Which one is best depends on the amount of flying you end up doing and how focused it really is on NYC-LON.

AA EXP has the best elite status benefits, for flying in the US or on cheap international fares, of the major airline programs. However to get EXP from AA you would have to fly the equivalent of 10 roundtrips from NYC-LON in business on AA/BA in a calendar year.

VS Gold status has fewer benefits and is far less useful for domestic US travel, but VS would give you Gold on your 4th roundtrip NYC-LON.