[Jedd]

Hardcore vim users use ctrl-[ instead. : )

Despite being two keypresses, this is usually faster to type, or at the least to return to home position from, and those keys are probably more consistently placed than the ESC key between vendors / models.

[rgoulter]

If you use "home row modifiers" (holding down f/d/s/a or j/k/l/; acts as Shift/Ctrl/Win/Alt), then it's less reaching for ctrl.

Although I'd also recommend making Esc available on a thumb cluster.

[Jedd]

This feels messier, partly because it's easier to fudge accidentally, but very much mostly because it relies on your configuration being propagated. I understand that may work in some shops, but generally it can't be assumed.

ctrl [ works everywhere vim is installed - no customisation required at all.