bonus is that Ctrl-C gets you out of pretty much any mode.
Also, while in insert mode, using ctrl-h for backspace and ctrl-w for delete word are really nice.
Better yet, ^[ is actually ESC in vi/vim, and works without a config change. I started using this last year and haven't looked back. ^C works well, but I recall it having some limitations in certain environments (though for the life of me I can't recall what they were).
In any case, I prefer ^[ to ^C, and hopefully you will too!
ouch...as others have said, CAPS LOCK is your friend
Why is caps lock your friend? I can't think of any situation where it'd be more useful than another key such as ESC or my personal preference, CTRL.