Emacs

I'd start with traditional emacs key bindings and a rudimentary initialization file. As you get more comfortable, increase the complexity of your initialization file to solve a current need. I'd advise not thinking about learning emacs but think about using emacs instead. If you're persistent, you'll use it to solve a set of different problems (using myself as an example, I've started using emacs as a replacement for two usecases--text generation and automated search and replacement on a large number of files--that I typically solved with shell scripts).

Not wasting a huge amount of time screwing around with emacs requires discipline as it's easy to screw around on things with little value (e.g. trying every theme you can find or searching for the perfect fix to something that only happens on startup) because it's interesting. I'd plan on a little time for fun but avoid going overboard.