All depends which charter airline, what contract ( permanent or part year), what pension plan( money purchase or final salary), what position on the command list if not already a captain...etc etc...
I think you and only you yourself can decide where you stand and what you want .....nobody else will be able to see it from your position. If you are already in the hold pool and have been told it's going to a 777 with BA then you have to see your age and where you see yourself in 10 years with each outfit..........????
I have to say from where I stand in my life it would be 777 with BA...