I am on Odin at the moment. It was the only non-full EU server at the time. It made the choice easy

I suspect a similar situation shortly after early access and launch. It may be the case you need to get there as soon as it starts for a choice - esp. If you have friends you want to play with. But who knows.

In the end, as lots of people haven't signed up yet so im not really sure its possible to tell right now, as we dont know what they are like to play with. And if the servers all exisit at the JP or EU+NA one datacenter pings may be very similar. Good Luck