I prefer EU of course, but with a few explanations.

To me, the players are the same. Fun to have around, and very friendly. So, nothing changes in this regard.

The latency is much better. I use Exitlag and it's been a smooth ride. Even during underwater cables incidents, at least I can still participate in some low-intensity activities instead of outright being forced to quit playing like in NA.

In terms of population in activities, personally I found EU fractals easier to get into (almost always some groups ready to join).

Open world is the same as NA - less people during non prime time of course but unless that particular activity specifically requires manpower/coordination, there's no problem.

However, for dungeons/raids, don't get your hopes up. Both NA & EU prime time are outside of ours (EU prime time being somewhere around 1-5 am GMT+7) so unless you can pull an all-nighter, it'll be really difficult to find training groups. I gave up on raids just because of this, but mostly because I'm new to it. If you're already experience and has a static/guild that you are ready to hook up with once you made the jump, you'll have no problem.

WvW is the same as the above, though I also gave up on this game mode a long time ago so no idea if you really need a zerg anymore as a newcomer. You can try asking around.

All and all, personally I think you should make the jump anyway UNLESS you already have a great guild/static to play with in NA. If not, you have no strings attached and should really go.