The one that works best for the individual rolling the ball
Please don't take this as an attack you, but statements like this really don't help the sport out at all. Even though it has some truth, what it really does to the general bowling community is this: they think that there is a specific ball with a specific layout out there just for them that it going to give them endless strikes. In reality what they should be doing is improving their game through practice and coaching.
I will admit, I did this 20 years ago. I wasted a lot of money on top end bowling equipment that I ended giving away to people when I wasn't using it anymore. Just thinking about it, instead of me buying three high end bowling balls and using that money on a top notch coach, just how much further in my game would I have been.
Don't get me wrong. Some of you are well knowledge in this sport and definitely understand filling gaps and replacing a ball in an existing arsenal.