Ehhh, the A-V is super fast and crisp.
It's the fastest, crispest cube I own, though, I put type C springs in it which have less tension than the default springs. Which means that it's even faster than other A-V cubes.
It cuts corners excellently.
With the little corner modification, it's even better.
It's too fast for my tastes though.
In my opinion the F-II is a well rounded cube, which is just plain good.
Since it's rounded, it feels better, and doesnt have the smaller outer layers that the A-V has.
It also has a nice feeling to it, also in my opinion.