I would say LCY every time. Unless you want to have a have an hour or so in the lounge pre flight.

LCY has better security, is quicker and the boarding process so much smoother.

Added to that you get the benefit of a complimentary G+T or two on board.

For the return leg from EDI I would say LCY all the way.

One final point about LNER is you can sometimes get cheap upgrades using Seatfrog but this isn't guaranteed.