[patrickgordon]

Rails.

You get lots of great stuff out of the box. Perfect for me to get up and running quickly for simple/side projects.

Writing Ruby feels nice and is always a welcome change of pace from a lot of the heavy JS stuff I am doing on frontend atm.

[herbst]

+1 for Rails.

When i have a new idea it takes me at max a hour to have to complete framework up and standing (Bootstrap/UI, User management, Databases, Deployment, ...) and i can start working on business logic.

[caspg]

I second Rails. Besides that it provides lot's of out of the box features, there are tons of useful gems. There is also really interesting new API-only mode.