I think Vox is good for a brand new player, especially if you plan to follow the Hero's Journey quest line. There are still plenty of people in low level zones like Crescent Reach, Blightfire, and onwards. Also, if you do HJ, you won't need to buy equipment in the bazaar, as you'll get a great set of items from quest/achievement rewards.

That being said, the population isn't as dense at higher levels it seems. If your goal is to experience all the quests and content, then I think Vox will be a great fit. If you want to speed things up and get to the "end game" a bit faster, than Firiona Vie might be a better choice.

Of course, nothing's stopping you from trying out both servers (-:



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