A macbook, because:
1) Apple hardware will always run OS X better than 3rd party computers, and hackintoshes are slower
2) The new macbook pros are epic nice =)
The MacBook would definitely be better since you're not only getting Apple certified hardware that works with OS X but you're also getting a years worth of both hardware & software support and the option of Apple Care to extend that support for another two years. Also, I hear nothing but nightmares about the Mini 9's keyboard when it comes to typing ... an issue that isn't known to exist on the MacBook. And some of the features like gestures which are native to MacBook's are known to work (at least for a time) with certain patches to the Mini 9, but is that all worth it? I don't think so. A computer is to be a productivity tool. You're tool is not being productive if you have a hard time typing on it and have to apply patches to get features to work that it natively doesn't support (with glitchy performance) - all of this without an ounce of support or a warranty.