On BA, if you can get the last row in C or on the UD rows 62 or 64 then you have easy aisle access. I always make an effort to get one of those but TBH when I don't I still take a window seat for the privacy and find aisle access not too big a deal to be honest - for the added privacy it's a small price to pay to have to climb over someone's legs which are anyway quite low at the end of the "bed". The other day I was actually upgraded to F on BA because an excellent customer service chap thought it was not right they had shifted me out of my private window seat into a middle seat (due to change of aircraft).

I agree with Clubman that BA C is far superior to LY F.