Garry's Mod Games

There are definitely a lot of great servers on Gmod. Depends what you like really. I mostly play darkRP but used to play starwarsRP. The experience massively changes depending on the server you're playing on. 2 different darkRP could have completely different experiences, and sometimes, feels like different games. I just found the server i liked the most and stuck to it. As soon as you get known within the community you can make a lot of friends and have some amazing experiences. And to answer your final question, it definitely doesn't not seem dead in my eyes. So many game modes to choose from.
Hope that helps your doubts about it.