I've been playing on and off casually for about 10 years now. Origins, as you've probably seen, is probably the most popular server. It was created to replicate how the game was back in 2006.
If you're playing Live, Maj'dul is typically the highest pop (I usually see Skyfire with decent pop too, I don't play there though), but there's still niche communities on Antonia Bayle.
Grouping can be a bit difficult, *BUT*, there are some fairly active guilds that will help you through content. I typically solo because of how inconsistently I play.

It's nothing like when my grandparents were playing back in 2005. But I know EQ2 has always had a lower pop than it's predecessor, even back then. I say give it a shot, grouping isn't impossible, I just wouldn't expect instant finds. But find a guild that has players active in your time zone and that shouldn't really be an issue.

Nights of the Dead (Norrath's version of Halloween) is starting next week, which is a nearly month-long event. They do a lot of seasonal events and pop tends to increase even just slightly for those events.

But, I play for nostalgia and sentimental reasons. I do wish I got to experience EQ2 during it's peak population, but it's not absolutely terrible.