What is the correct folder or subdomain?

Question

CMS

There is a project (real estate bulletin board) how best to optimize and promote regions on a subdomain or in a folder?
The site will be thematic, I plan to make shops (agencies) on a subdomain, since the domain should be short, it should look normal (example: blagovist.an.ru), how will this affect promotion?
How to properly promote:
1. Region folder / store subdomain
2. Region subdomain / store subdomain
3. Region subdomain / store folder
Very help out with advice, I have already broken my whole brain, I have climbed a bunch of forums, everyone's opinions differ.
Thanks