It would all depend on flight times, connections, layovers, etc ...
We're also Canadian (Edmonton) and have flown both airlines ... we actually prefer Delta because their flight times are much better for us. We've never had problems with Delta losing our luggage (knock on wood), even with a layover. Our luggage is usually one of the first to arrive on the carousel in Orlando. I'd say 99% of the time our flights have been on-time, with the rare exception of mechanical difficulties maybe twice in all our flights since 2003.