I am not a big fan at the moment but Westjet pricing to the UK is more attractive than AC. Have looked at getting a Westjet branded credit card to gain a Companion Voucher. My limited research has very mixed results on the value. Some love it but others say they can never use it.
My question is how restrictive are the flights that one can use it on. I would be booking. YYJ to LGW or LHR via Calgary.