Earlier quoted context omitted.
shift Z Z is faster.
Debatable and depends on length of time shortcut has been in use. I can type :wq like a madman. My finger can slide straight from w to q, whereas with double-z, I have to pick my finger up and put it back down. So much movement! What next, you want me to run a marathon?
:wq =
ZZ =
As someone with mildly poor dexterity (and I don't touch-type with all my fingers, I mostly use my index fingers), the second approach looks somewhat more interesting to test.