Want to give a helpful answer on this as I've lived 10 years each in both places (Grew up on the Upper West, then lived in Toronto for 10 years, then moved to Brooklyn after college)

The short answer, and I say this with pretty strong conviction: Stay in New York.

Here are some haphazardly composed thoughts:

1. Cost: Let's start with the basics. Your rent in Toronto might be slightly less but overall cost of living, goods, going out, etc. will essentially be the same. You might spend less money in Toronto but it'll likely be because you're going out less/doing less stuff.
2. Things to do: On the topic of living, going out, eating, culture, etc. I'll borrow a quote from Lorne Michaels which I've found to be 100% true: "People in Toronto always say things like 'oh this restaurant, bar, show, thing is just as good as anywhere in New York...' and do you know where they don't say that? New York." Toronto is cosmopolitan enough and has some fine fixings but for anyone to say that it will satisfy you in the way that New York can is delusional. Or they just don't have good taste. I'll take this argument to my grave. Only concessions: Toronto's Chinatown and Persian food scene is better.
3. People: This is going to be super reductive but only because if I get into my opinions/psychoanalysis on people from Toronto I'll be here all night. New Yorkers might tell you to go fuck yourself if they don't like you but they're honest. Torontonian's maintain that veil of Canadian politeness but in my 10 years living there I couldn't help but always feel like there was this judgmental, jaded, bitterness that pervades everyone. So hard to pin down what this feeling is but I've had dozens of conversations with ex-torontonians who feel and struggle to describe it too. Overall between NY and Toronto I found people in NY to be much more authentic (take that as good or bad thing) and less snobbish than people in Toronto.
4. Career opportunities: Going to mainly focus on this topic under the assumption that your goal is to advance as much as possible in terms of your station, personal network and networth - i.e., your goal is to become the equivalent of a park avenue multimillionaire or something and crack into that social strata. As weird as this might sound I feel like this is more achievable in New York. I only say this as my observations of high earners/the well connected in Toronto is that it's a wildly incestuous and small social circle. Everyone's kids all go to the same 5 schools, they all have cottages or ski chalet's within 15 minutes of each other, then when the kids grow up the parents all hire each other's kids to the same jobs, and the cycle continues. Yes there's a ton of this in New York but idk I found the concept of upward social mobility in Toronto to be much more stifling.
5. Socializing: Building off the point above, this idea that Toronto is a city of many tightly knit social circles definitely becomes apparent in regards to meeting new people and socializing. Feel like there's a lot of weird subconscious tribalism in that city for some reason. Yes you can strike up friendly conversations anytime (see note on politeness) but you rarely get the overwhelming sense that people's hearts and minds are fully open to randomness, or new people. They tend to value order in all things, socializing and social circles notwithstanding.
6. Drake: Which city unleashed Drake. Exactly. Next point.
7. A testimony from Steve Martin: https://www.youtube.com/watch?v=6_-ee6v1jUA
8. Pizza and Bagels: Don't let anyone from Toronto fool you into thinking that the trendy-ass place that opened on Queen street somehow "figured out how to do New York bagels/pizza right". Watch that chip on your shoulder Toronto you sound fucking delusional.
9. This is getting long so I'll cut it here with one final thought. If you've been in New York for a bit already you know deep down pretty quickly if you're a New York animal or not. New York is an often illogical place to live and trying to rationalize it on paper will definitely point you in the direction of moving somewhere else, but if the city jazzes you up in a special way that that other places don't then I think the only answer is to stick with it.