I have lived in both Toronto and Vancouver, and honestly, it's a tough call. Rent in Vancouver is probably higher on average, especially if you're looking at downtown. You'll get slightly more for your money in Toronto apartment-wise, but it's still crazy expensive. Groceries are fairly similar, maybe a touch pricier in Vancouver depending on where you shop. Transportation-wise, both have decent public transit, but Toronto's TTC is more extensive, and might save you a bit if you rely on it heavily. A monthly transit pass is pretty comparable though. The real killer in Vancouver is probably eating out – it feels like restaurants are just that bit more expensive. Ultimately, it's close, but I'd give the edge to Toronto being slightly more affordable, but don't expect a massive difference. Location within each city matters a lot too!
honestopinion: Toronto's public transit being more extensive is a big plus if you don't want to rely on a car.