Server Question
With the new megaserver system it will mostly matter if you want to WvW because that remains something bound to your “official” server. To a lesser extent it will matter if you want to interact with the same people a lot (see: RP) because the megaserver does try to load people of the same server into a map, with varying amounts of success. As of tomorrow’s patch, it won’t matter at all for guild membership perks because those will be cross-server.