I'm starting to emphasize lounges when I fly BA more, and just sleeping onboard. In the OP's case, I would choose F to get Chelsea and CCR access, so I can enjoy those aspects and maximize sleep. If you drink, and/or want good Champagne (Dom, LPGS etc), Scotch, etc then what you consume at Chelsea & CCR could justify a good chunk of the $2000 premium.

If you want to minimize airport time and save as much cash as possible, just stick with J.