For someone ex-YVR, I'd have to go with CO.
With a quick perusal of DL's website it looks like they only have 3 regional jet flights daily to SLC.
Compare this to the CO/NW/HP partnership with flights to IAH, MSP, PHX, and SEA. I think you'll have a lot more opportunity for international and transborder travel with CO.
Canadian travel with both pretty much sucks, but you already knew that.
[This message has been edited by skofarrell (edited 11-27-2001).]