The server (world) you choose only matters if you play WvW (World vs. World). The PvE is not based on your server choice. Some are specifically marked for DE, FR and ES (in the EU region). So basically all the servers without a language flag are mainly English speaking. But as said above, that doesn't matter for the open world PvE, dungeonsWorld is the term used to indicate the group of players on the same team in World versus World; it has no impact on open world PvE experience. There are 51 worlds in the two regions in the Western Hemisphere: 24 in the North America (NA) region and 27 in the European (EU) region; players share instances with others from the same region, but never with those from other regions. Free transfers were only possible before a patch a few months after release. Transferring always costs at least 500 gems since then. The good news is, it only costs 500 gems to transfer to a medium population world (server), which is about $7, although you would have to spend $10 because the lowest amount you can buy is 800 gems.Alternatively
Megaserver is the Guild Wars 2's version of how both open world zones and instances exist and how they are populated. All players from the same region (North America, Europe, or China) are able to play together automatically, as they are placed into the same instance as everyone else in that region, until the game determines that the map is getting full, at which point it creates a new instance.
On the other hand, the conversations I've seen/participated in in EU tend to be nicer (generally cleaner, less trolls, less drama, and less "Do this for me!") Depends on time zone and more importantly language. Whilst in NA, the predominate speaking language is English, so you'll find more ppl talking in map chat. .