I think Control is the best choice. It makes it much easier to use Control-modified commands, especially in Vim/Emacs. For Vim, you can use Control-[ to exit insert mode, a command that becomes much easier with Caps Lock remapped to Control. I use Vim, and I prefer more convenient Control-modified commands over having an Escape on home row. Besides, having Control on home row and using Control-[ is basically like having Escape on home row :)