I prefer info to manual pages and even readthedocs websites by a large margin. Emacs' info reader is great, it keeps track of your visited info nodes as a tree, generates custom indexes for you and allows you to navigate by visit history, node name, index entry and more.

The only downside is that you can't embed images in info, so you end up lots of ASCII art flowcharts ava box drawings. But that's true of man pages as well.