A lot of folks map jj for ESC and uu for underscore.
However, what this means is that on typing j or u, vim waits for the next keystroke before displaying or doing anything.
I can't remember where this used to hit me. Perhaps some abbreviation with u ?? I notice I've commented off "uu" but still have "jj".
I still go up and slam the ESC key after 20 years of vimming. How do i get into the habit of C-[ ?
The habit is only formed by training. When I first started learning Vim I used the arrow keys for navigation. I recently null'd them out so the don't work. I couldn't do a damn thing. I still use the arrow keys.
Here's a vote for the capslock/esc remap. I've got it as a global remap and have gotten used to it in other apps as well (canceling a dialog, for instance). Couldn't live without it.
c-[ is Escape (displayed as ^[ in vim). Also, it isn't obvious for beginners where c-[ is located on non-English keyboards. And it's two keys to press. I'd still prefer Esc. The fact that the key is usally located outside of the main typing area reflect its meaning. Get me out of here.
A lot of his keybindings are are similarly nonstandard.