The problem I'd see with putting a campus in Toronto would be that the transit infrastructure is bursting at the seams. Underfunded public transportation, expensive and underfunded regional transportation, and congestion along all major routes during the day. Along with the sky-rocketing cost of living there you'd filter out a lot of candidates or force people to commute over long distances on a choked network.

YYZ is a decent airport but it doesn't compare to ATL or ORD.

> - a strong existing tech workforce and universities

I'm not saying those of us who stayed North of the border aren't great but a large portion of our talent does head South for the opportunities. Funded technology companies in Canada are hard to come by. A good 80% of the jobs here are for digital agencies. Even Google and Microsoft keep most their technology jobs mostly South of the border despite all of the incentives they're courted with.

Immigration in Canada is a lot more friendly but I don't think that's going to out-weigh the benefits of the other cities listed. My money is on ATL or ORD.

update: 80% is just a rough guess