I think most people go to Atlas Blueside and most people zoom through Mercy redside
You should find plenty in Cap Au Diable redside tho
and welcome to the game
Virtue Server Forever !
Pure White Lightning - Level 50 Electric Brute
Purple Drop - work in progress Axe/Shield brute
Blue Icefall - Level 50 Ice Tank
@Blue Lava
The crowds will also vary depending on which server you chose and the time of day you play. Freedom and Virtue are the highest population servers and maintain a good number of people all hours of the day and night. Atlas Park on hero side is where you find most people hanging out.
Also, keep in mind that this game is heavily instanced. At any given time, most players online are in missions, so you won't see them. There's also a lot of zones for people to be spread through. Also, with the Incarnate content out, a lot of people are playing their level 50s in the higher level zones.
That being said, there are some easy ways to find teams in this game, if that's what you're looking for. The first is to join a good supergroup. The second, and probably more important way, is to join a global channel. I recommend stopping by your server's forum, and asking what some good global channels are to join for teaming.
Hope this helps!
Let me never fall into the vulgar mistake of dreaming that I am persecuted whenever I am contradicted.
~Ralph Waldo Emerson
"I was just the one with the most unsolicited sombrero." - Traegus
Last but not least - the 50s are still grinding away at trials, so you'll see quite a few (depending on server) in the Rikti War Zone, Pocket D or (more rarely) Cimerora.
Also, Friday night, Midnight eastern, Virtue server, there's a weekly costume contest redside in Port Oakes.
In general (it does vary server by server and day to day):
Blueside:
Atlas park has lots of people
Peregrine Island has lots of people
Talos Island has a decent amount of people
All other zones feel like a wasteland even though they are not (except for Galaxy City, Boomtown and Perez Park, they pretty much are wastelands)
Redside:
Cap au Diablo has lots of people
Grandville has a decent amount of people
Sharkshead Island has a decent amount of people
All other zones are wastelands.
If your server uses it for iTrials, the Rikti Warzone is overrun with 50s who will ignore you unless you are starting an iTrial. If your server uses it for iTrials the Pocket D is overrun with 50s who will ignore you unless you are starting an iTrial.
If you are on Virtue, Pocket D is overrun with people you will either wish you could ignore or who you will really really enjoy.
Yes on those last two bits I am exaggerating and being a bit of a goob. That's who I am.
"Hmm, I guess I'm not as omniscient as I thought" -Gavin Runeblade.
I can be found, outside of paragon city here.
Thank you everyone at Paragon and on Virtue. When the lights go out in November, you'll find me on Razor Bunny.
Are you sure people aren't just avoiding you? Not everybody wants to be seen hanging out with Someone Crazy. 
If we are to die, let us die like men. -- Patrick Cleburne
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The rule is that they must be loved. --Jayne Fynes-Clinton, Death of an Abandoned Dog
It probably varies a lot from server to server. On Victory there really is no 'hanging out' at certain locations unless you count the people in Pocket D forming up for trials. If you want to find people there for other things you use the global channels. People do hang out in chat but not at locations.
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@Inquisitor
On Union and Defiant people tend to hang out in global channels rather than game locations, although Pocket D is used a bit and the roleplayers use some other locations too.
Octavian Vanguard
@ohmsEU and @ohms 2
Badging character: Bimble on the Union server, Badgehunter.com and City Info Tracker.
It's so empty in the newbie cities in Paragon city and the Rogue isles, I barely see anyone.