New Credit Cards for $15k Spend

You already have the Marriott card and Aeroplan cards from both TD and CIBC. Another Amex is the only game in town if you want more Aeroplan or Marriott points. Consider the Amex AP charge chard, AP Reserve credit card, or either the Gold or Platinum MR-point-earning cards which can be transferred either to Marriott or Aeroplan.

Agreed with @Kiraly.

If interested in the U.S. game at all, AMEX U.S. has some options. 125K Marriott Bonvoy points on the Bevy for $4K in 3 months. 150K Marriott Bonvoy points on Brilliant for $5K in 3 months, so not as good return, but certainly filled with several great benefits incl. Platinum Elite status. Or same thing with the Canadian side of things, any of AMEX U.S.'s MR-earning cards will also be transferrable to Marriott Bonvoy at 1:1.

If you have an ITIN, Chase opens up a lot more doors, also to AC Aeroplan as well as Marriott Bonvoy.

I don't know if you are interested in business cards or not, but amex business business gold, business platinum and business edge all earn MR points that can be transferred to aeroplan or marriott. They all offer good sign-up bonuses (90K for the $499 platinum, 75K for the $199 business gold, and up to 77K for the $99 business edge). Plus the business platinum offers marriott gold status.