6A/F always if I can for one simple reason: the double seat pocket space you can get if the pax in 6B/E don't use them too much. Has been pretty helpful for me as I like to pull my laptop and some other stuff out to work during the flight, but put my (often well stuffed) backpack in the overhead. I'm not particularly wide and don't have any issues with the reduced seat width.

Otherwise, will go for any of the remaining PC seats as I value the view not being blocked by the wing over the extra legroom in 17.