Having done UK regional flying, the sandpit, and now BA LH, I – personally – find BA the easiest of the three. That said, it probably helps being on the 787, as everyone else is doing our flying for us. 
Also, I don’t mind working weekends and am in a position where I can prioritise lifestyle over cash or command, so I’m quite content in the RHS. I quite understand that others will have different priorities, for all sorts of reasons. But like what Wiggy said:
many will find the model BA seem to be aiming for and one which BALPA seem to less and less able to moderate will be one that is unsustainable over a full time, multi decade career.
I couldn’t agree more. Being late to the party, I’ve got a maximum 20 year career with BA, but I can’t imagine being full time until retirement – part time is the only way to make the job work long-term. One could ask whether it would be any different in low cost short haul? If not, I’d suggest the workload / sustainability issue is an industry wide problem, and not restricted to BA.