Which server do I play on?

You can play on any server you'd like. When loading the game, it will choose the best server for you that is closest to your location.

You can switch the server you want to play on by clicking on the drop-down and selecting which region you'd like to play in. Keep in mind, the further away the server, the more latency you will have to it. (Delay in response time between you and the server)