Agree with all that wingswinger has said.
The big question to ask yourself is what type of lifestyle do you want if and when you leave. If you plan on living a long way from any potential job, then long haul may be better, if you want to live close to work and would rather spend most nights in your own bed, then perhaps short haul would suit.
I tried living out of a suitcase, it didn't suit me. I now work short haul and it works far better for me and my family. I'm not saying it's better, just that it suits me better! By the same token I know lots of mates from our background doing long haul and are happy with their lot.
The 'hot' airlines at the moment would lead you towards Virgin if long Haul, and Easy for short, BA still a very good employer, but seniority is all there and the pension is no more for new joiners. The snag is that this game changes quickly. A couple of years ago Easy lost lots of guys to EK. Now almost no-one is leavng easy and we are picking up lots of EK guys who have had enough there.
Perhaps you need to ask yourself where you want to live and what type of lifestyle. The most important thing in life will no longer be your job, so make the job fit the life that you want rather than the other way round!
Pm me if you need some more gen. To stay or go is probably the toughest call you will have to make.