gmod darkrp server or other?

Well... It depends. You have to be able to A. Code somewhat B. Manage a community of players C. Manage a staff team. If you can't code then you wont be able to open up a server in the first place. If that's your current issue there's plenty of resources around to help you out. It also depends on your personality. If your a dickhead owner that doesn't care about what his community wants then your going to fail. You have to be able to manage and do a wide variety of things. There's a difference between owning a server and profiting off a server.