Air Canada is the best job in Canada, but that's not saying much.
There is no doubt UPS pays a lot more than Air Canada.
In the 2012 government forced contract we lost so much and have since fallen even farther behind...
I'm a top third 737 Captain on the old pension plan and I'd go to any US Legacy carrier tomorrow if I could... I've never really looked closely at UPS/FX but I understand pay is tops there too...
Anyway, the things we do to live in Canada... it's still a pretty good job at AC, upgrades are around 2 years right now on all the narrowbody fleets. Lots going on with the contract re-opener next year, the Air Transat purchase, and the A220s starting to come later this year.
If you have any specific questions on AC, shoot the puck... but unless you're really adverse to a commute or night flying or something in the UPS contract/lifestyle it seems an easy choice...
Good luck.