Probably against the consensus, I prefer eastbound. Maybe because I'm going home but I also find the lounge more welcoming at JFK. It tends to be less crowded and edgy. I think the timing has a lot to do with it though - do you want to chase the sun, or rocket into darkness? Despite some reports to the contrary, I find the (albeit tiny) view exhilarating.

I would like one day to do the BGI > LHR trip - the idea of going straight to Mach 2.0 without the initial delay sounds great.