Not too much experience of BA at LGW, however on the 20-30 flights I’ve take to/from there, the crew do seem friendly and the service has been very good/excellent. e.g. Alison and her team in CW from BDA at Xmas.
At LHR, I need to split into WW and EF.
WW has always delivered a minimum of a professional service, sometimes a little ‘detached’, but never rude.
EF has been a real mixed bag, with some very good crew and some who seemed to lack the customer facing skills required for the job – i.e. on one CE flight from Paris to LHR, not a single smile all the way, from any of the three CC in the cabin.
I find a lot of inconsistency on most European airlines, even Air Malta, but in the latter case it is normally that certain #1 crew members have their own way of doing things and all are good once you get used to the differences.
Fortunately, with such a small airline, frequent travellers and the crew often know each other so the atmosphere in the cabin is normally relaxed and friendly.