20 years ago I had a chance to go to AC and I went to CX instead. I never regretted my decision until the last 4-5 years when a combination of a degrading lifestyle and realizing that my nearing retirement will be pensionless while my similar aged friends friends at AC will have a fantastic pension for life. Granted, I don't ever think I would have ever matched my "total" CX salary at AC while employed but with their pension it certainly would have exceeded my overall take from CX.
Personally, I think you have to look at how many years of seniority you will give up and your current age. If you can get 20+ years at AC then it's probably an easy decision but don't go there with rose coloured glasses either. They have some operations (2-man) which are much more difficult than our's but overall, fatigue is less and you have a life!