You can find out quite a bit of info from the serverlist here for most servers:
http://www.eqemulator.org/index.php?pageid=serverlist
Just click the "view" link for the server and it will show information for that server and a website/forums URL for most servers that have them as well. The Legends servers are servers that have large player numbers and have been around for a while. The green Preferred servers are servers that have also been around for a while and have nice player numbers too. There are some regular white servers that also have some decent populations and have been around a while too.
I would recommend trying out a few servers that have descriptions you find interesting for them. Any server with more than 10-20 players on them are probably worth checking out at least. As far as custom content goes, I would recommend checking out any of the preferred servers. Though, unless you speak/read Chinese, you might want to avoid the servers that have "CEQ" in the name, as those are mostly designed for Chinese players other than KMRA, which is an American server with a Chinese language option for it.
For any servers that have a website, you can always check the websites for further details about that particular server.
Welcome to EQEmu. I think you will enjoy it