I'm new to all of this, starting from scratch, and looking for the current best alternative for Mac OS X 10.11 for TextWrangler now that it's discontinued.
TextWrangler was always a feature-subset of the paid, full-featured BBEdit, from barebones.
Without a paid license, BBEdit runs just like TextWrangler & is a direct replacement for it.
Same maker, same look, same feature-set, opens all your saved documents, runs without an added license. The only action you need to do is install the app.