I'll bet you $5 they settle on the stroked box like Facebook did.
Nifty find. I like the stroked version.
Stroked one will win, but it's alignment is jarring. Does it need to be as wide by default? Could be about a third as wide and then extend when user clicks it.
Minimal is pretty, but it's too minimal. Could do with some indication of where the cursor would appear when you click it.
Genuinely surprised this even warrants testing. The stroked one is hands down going to win, obvious always does. (and for good reason)
Visually I prefer the minimal version, but I think the stroked version will perform better. If the difference in performance is minimal, I wonder which version they will go with. I also wonder what they consider minimal.