Just try to find one in your region… not a lot “tuning” that can be done on this front.
I'd recommend putting a Media Subdomain (https://media.aus.social) or similar to front your traffic. Read about that here.
AWS S3
Do not for any reason use AWS S3... they charge you for storage and upload/download.
I was using AWS S3, and once more than a few thousand people joined... it went from $30 to $1000s a month for something Wasabi charges $10
Wasabi
I'm using Wasabi, because they are very cheap. They have a history of outages in their primary regions, but in Sydney, I haven't experienced any issues with their service (as of writing).