All the servers are physically located in the US with the exception of the legendary server Mordor that just opened a few days ago. You need active subscription for that.
For the normal servers marked as EU Laurelin has less players that Evernight but has more serious roleplaying scene if that is something you're interested in. There are also servers for Germans and French.
If you can pay for the subscription I'd strongly suggest hopping in the Mordor server. It's in the 'busiest it gets' phase where there are soo many players having fun at the low levels. I'm loving it. The initial hype will die after few months so now is your best chance.