Zaviel, Gelidra, Blightweald and others too are highly populated around prime time, and I'm sure some others too
So just jump in . If you decide you don't like something on a shard, you can (after reaching level 15) always decide to transfer to another shard for free (once a week) - or just create a new toon on another server of course
How ever do know that highly populated do not always mean high in the lower levels, most people are level 60 and is moving in those area were endgame is going so if your hometown seem low on population it is because most people camp out in tempest bay were both guardian and defiant can be on same spot.
Also if you want to change shard you can do this as soon as you reach level 15, and you can change 1 time each week and it cost nothing to do so. Also it does not really matter what shard you choose since you can jump between them at any point of the day, as long as you have a anchor (player who invite you to a group) on the other shard to port through.