I need to take a late evening flight leaving Midtown Manhattan (right near grand central station).

I have an option of 9.30pm EWR (BA) flight or 10.30pm JFK flight (mid week). I have precheck, no baggage, and don't mind cutting it close.

I'd like to stay as long as possible in midtown before leaving, which is a better option?

I'm asking on AA forum not NY becuase it relates to realities of kerb to plane timings as well