Where is the most sustainable place to live: a big city? spread suburbia? farming country?

I often question where the most sustainable life can be lived in Canada. Maybe in the centre of an urban city, what about suburbia, or in the country living off the land? In my opinion, I'd rank suburban life at the bottom of the sustainability potential, as it is usually a life of large homes, spread out utility services, dependency on cars, shopping, dining, and entertainment predominantly happens at big box, big-business multi-national venues. Living in a big city means that there are many people, with many different interests. Because there is groups large enough interested in unique things, that wouldn't likely survive in a suburban environment, stores, shop owners, and community centres cater to these unique niche groups of desires. This means that farmers markets abound, a celebration of local food and community that just wouldn't be as feasible in every suburban neighbourhood as people are more spread out, and so, less people per area would show up to the markets. Living in a city means that almost everywhere (and I can speak here for Toronto only...) you are a walk away from little shops and restaurants that are often locally owned. Further, living in Toronto means that it's often more of a hassle to drive then to take transit, walk or cycle. But of course, there is a whole other group of city dwellers who don't see these things I'm speaking of, and instead live the city life quite differently... And then there's the thought of living in the country, where you can potentially live off the land completely. I've never lived in the country, so am unsure just how sustainable it actually can be, but have always been interested to try it out, farming and living in harmony with the land. So, where can the most sustainable life be led? I don't know. But I do know that there are tons of choices that we can make every day, no matter where we live our lives, that can contribute towards environmental conservation, local economies, political and social justice. You just have to make that choice. Cities are often a place where something happens for everyone in a big way. That means that where there is one person interested in gardening, there will be many (like for instance - Seedy Sunday that I attended today, which so many other folks in Toronto also attended to exchange seeds, to talk about seedlings, garden plans, worm poop, and growing yummy food in community spaces, backyards, or appartment balconies!) But it's also a place where some people seem always to be consuming - food, culture, music, art, sport, material goods. Sometimes in a healthy way, other times, not. And so I wonder...where can the sustainable life be truely lived in practice?