Depends on the time of day.you want to fly, but LCY is certainly a more seamless experience. Arriving back from Scotland, I'd definitely be looking at LCY as LHR arrivals offer an infinite number of factors that could throw a spanner in the works.

I don't even mind missing out on the First Wing amd GF, if I can use LCY (I'm the opposite of you, LCY is a no change DLR, whilst LHR needs my motorbike or a few changes on public transport)