Toronto might be the best city in the world.
The tuition costs are better.
And if you ever do choose to relocate UofT has the reputation of being our "Harvard" and will give you tremendous pull anywhere. On par with that of HYS.
I don't want to start a major argument or anything but:
1. TO is a great city but I think its a bit overly subjective (and Mel Lastman-like) to call it possibly the best city in the world.
2. Let's not carried away. UofT does not have the sway of HYS and is not on par with those schools in almost any meaningful way.
You are definitely right that going to UofT is a lot cheaper and you do avoid pesky visa and immigration issues, which are probably worse now in the post-911, illegal immigrant paranoid US. If you want to stay in Canada, then yeah, UofT is a no-brainer and its better than HYS.
I personally would take the upper half of the T14 over UofT with extra sensitivity for money offers. Hopefully in 3-5 months time, I'll be in a position to actually make that decision.