I'll go ahead and leave some insight on servers that I've played.
Colonial Marines
Server features marine-versus-xeno combat with a major xeno bias and is known for the amount of drama that it has spurred over their closed source licensing being illegal due to the means of acquisition.
Yogstation
A poorly managed server. Should be fine to play there for a bit, though the 'mins are banhappy.
Baystation
Poorly managed military high-roleplay. Most rounds consist of "lolol antag" and then "GENERAL QUARTERS" and then dead antagonists.
/tg/station
Interesting to say the least. One of the OGs. It's usually pretty fast-paced.
Goonstation
Fast-paced as well. Pretty nice.
Polaris
Baystation fork. Known for snowflakes and less-than-prideful content.
Fallout 13
Too many servers to dictate specifically, but this exists.
Hippiestation
JamieH, the new owner, is an alright guy though there's a lot of drama regarding his management of Hippie. The murderboning has been quelled by the new host, so far, so it might be good to get bearings on.
Aurorastation
High roleplay with an emphasis on poorly planned events. Used to be the circle of drama after another server, Unbound Travels (revived from another server that was a drama-starter) was shut down.
It's all in all a fun game, but it depends on where you decide to play. It's advised to find a codebase you're interested in, read the wiki, download the server files and compile them, and then actually play around with it a bit before going live.