Try this task for an example: underline an arbitrary line of text with '=' characters. In vim that's 11 keypresses across 3 operations, possibly less if there's a shortcut I haven't thought of. How many keypresses does emacs take out of the box?

Emacs, especially with paredit, is fairly well optimised for editing s-expressions and the like. Vim is very well optimised for line-based editing, but I don't get on with its buffer management at all.