Your comparisons are noble but don't wash.......CX pays for rent so that point is moot. Slightly lower salary? Try seriously lower for the same years of service, not to mention the tax implications.
I've worked for AC and CX and as a single young guy asking the question, CX is the best option all things being equal.....if you have other considerations ie kids, family obligations, rich wife etc...then things could change, but the expat life is exciting and opens up a whole new world.....the Tim Horton's at Pearson on the other hand.......