The ones where the data says demand already exists. Country-level performance shows where your downloads already trend up without local effort, which is the clearest signal a market is pulling. Studying how competitors localize there tells you the second half: if the leaders invest in local keywords and creatives, the market rewards the work, and if nobody bothers, there may be a reason. Follow evidence, not map size, since the biggest market on the map is rarely the one readiest for you.