Most Populated Server?
You heard wrong. They use a megaserver technology to sort overflows according to server, party, friendslist and also to combine servers on less used maps. Even the most out of the way cities have a bustling population. There are more complaints about too many players at events rather than too little.
For WvW it really depends. The higher ranked servers have more round the clock coverage, but even low ranked servers will queue up maps on reset and during prime time. As the week goes on there is less activity in all tiers as the matches reach resolution and players move to EotM or PvE.
https://leaderboards.guildwars2.com/en/na/wvw
Imo, a new player would fare better on a Silver league server since you’ll most likely get steamrolled in the top tiers before you have a chance to learn the game mode.
If Guild Wars 2’s are dying than no MMO in the western industry, aside from WoW, is alive.