I think one of the features that I currently wouldn’t be able to live without is multiple cursors. Just a few examples of what you can do with them:

Of course these are just examples, once you have used them in practice you will understand their power better.

I think the main reason I prefer them to keyboard macros and regexp manipulations is that using multiple cursors is visual and easy to get correct step-by-step. When you make a small error you can always easily undo.