I have started using visual studio team services, it is really good and it's free. https://www.visualstudio.com/team-services/

I used to use team city, octopus and jenkins in previous jobs. Personally, it is really easy to use and you don't have to use the microsoft stack. It supports Python, Ruby, node etc... It feels to me like they waited to see all the good bits people have done and then just implemented them.

I didn't want to manage a server so it is perfect for me.