It is all very well number crunching how much more you might make in one airline over another, but money is not everything in life.
I've been in this industry over 20 years and I find the happiest pilots are those that have good t&c, thats a given. But added to that, variety, choice and lifestyle play a big part in overall satisfaction. If you are looking at your whole career, working for an airline where you can change fleet, LH/SH and role is almost equally important to remuneration. For this reason, BA, while acknowledging that it is not the gold standard that it once was, is the best bet for a pilots career, IMHO.
I think it is also fairly pointless to predict who will be solvent in 25 years time, who, 25 years ago, would have predicted an industry like we have today?