Its been done to death, on this thread and others. there are pros and cons a plenty.
From my perspective, if you are in your 20s/early 30s and single(ish) then BA is still as good a gig as any. The main reason being you can bid to move around between SH and LH every 5 years. I find that kind of career choice liberating and it helps stoke up enthusiasm for the job.
Realistically, most join and do around 5 years A320 and then move to a LH fleet, then take stock after 5-10 years about a SH command. Many stay LH as the lifestyle is to their liking. Very few actually do a new Type Rating every 5 years/jump around between SH/LH but it is possible if you really love Groundschool.
Joining straight onto LH is a nice move for already experienced guys but you will sit at the bottom of a very long list with hardly any appreciable movement for quite some time.
If you want big money early then forget it. My mates at Locos are all far better off than I am. That said you can be at £100k p.a within 7-8 years as a LH F/O - with overtime and bonus.
Glad to hear the patient swimmers are being rewarded. A350 joins the fold in 2019 for anyone who fancies it.