I'd be all for YVR or YYC.

I was puzzled at their additions of Puebla and Villahermosa. Copa already flies 5x daily to PTY from MEX (plus 1x daily to BOG), which is only 1.5 hrs from Puebla. Villahermosa is a Pemex/oil center. Definitely not a tourist destination. (It's the most unpleasant climate I've yet encountered in Mexico -- 40 deg C heat with high humidity.) Maybe they think there's enough Pemex/government customers to make that city work.

There's another route they do that even tops the four you mentioned in distance -- PTY-MVD is 3,396 mi. (I'll be flying that one soon.)