I'm more loyal to AC because of Aeroplan. I try and stay with AC (and at Tango-plus or higher fares) until I make Elite each year.

Then I still fly AC (but on Tango if I can) or a cheaper Star Alliance partner because I can use my status for short line-ups and lounge access.

If I didn't have status, knowing how hard it is to get good value for my points, I'd not bother and just go with cheapest/most convenient routings (and use the savings to buy a lounge pass like Priority Pass.)

So I'd say Aeroplan makes me more loyal because of the perks I get with status.