It wasn't heavily utilized when I worked at AWS, until 2024.

If your customers are clusterrd in Toronto and Montreal, it probably makes a lot of sense to use ca-central-1. If you've got a lot of customers in Western Canada, us-west-2 is gonna have better network latency.

Other than a couple regions that had problems with their local network infrastructure (sa-east-1 was like that), there's little or nothing to differentiate the regions in terms of physical infrastructure and architecture.