[Ganxxta]

I'm afraid its inferior just by comparing official BMW data for both, the ZF8 usually is rated faster than manual while using less fuel.
The Aisin however is exactly the opposite, its rated slower than manual and is using more fuel.

(comparing german versions as you guys won't have the manual in the X1 as far as I know)

However after watching some reviews some say its fast and smooth and shifts at the right time to the right gear, so it can't be that bad.