Amex is very conservative in canada for credit. They are much more liberal with charge cards since you have to pay 100% back every month so they know immediately if you are in trouble.

Charge cards have a dynamic credit relationship so your account is always under review and the barriers can always shift. You may find this is a better fit for you longer term. The Gold Rewards charge card is a flagship mid market product that has much better perks and points for most users than the choice cards, which are now discontinued and you are currently grandfathered but that could change anytime Amex chooses to streamline it's open products list.