What country will the servers be located in?
According to the Q&A, the current test server is US based, and if there is an influx of player which requires a second server, US and EU will each get their own server.
Keep in mind though that these are the dispositions for the testing phase, we have no info on what will be after release.
The last alphas had no significant lag or disadvantage to EU players despite server being in US. I think a Brazil player only had minor lag.