To lose that last 10 pounds that are hiding your washboard abs? Either will work, those last 10 pounds are lost in the kitchen. That said, I am a big fan of Insanity Asylum.
P90x vs Insanity - Page 2
Doing P90X on it's own will not bulk you up. You're gonna have to add extra calories to get mass. It will get you ripped though, but will kill your cardio. I do MWF P90X and TuThSat Insanity. I'm 6ft 165 and would probably ideally add another 7-8 lbs of muscle. With exercise and diet you can shed pounds quickly but it takes time and dedication to add muscle.
I'm not sure why you would want to drop 10lbs for basketball. Basketball is all about upper and lower body strength if you want to bang around in the post, which at 6ft you probably will be.
Insanity is very high impact.
I like P90x much better. Lower impact, but still keeps you burning.