I think the Cardinals are a better fit for Jansen in terms of a trade partner.
Cards have some intriguing OFs. Tyler O'Neill would be a great add and buy low if the Cards are willing to move him. I know he's a RHB, though if he's healthy he could provide a 5-6 WAR season from one of the corners. 2 more years of control, same with Jansen. Jays could then trade one of Teo or Lourdes for some pitching.
Lars Nootbaar would be ideal since he's younger and has more control, though likely any deal would involve Kirk or Moreno.
I think a Jansen/O'Neill swap actually works well for both clubs.