When a couple of my friends (they're brothers) started playing, they both bought Spyder Pilots on my recommendation (they wanted wal-mart's best, and didn't know what to get). When one bought a barrel kit for his, he liked the 18" combination. His brother bought a 21" Tiller just because he wanted a longer one.
Before long, he was breaking nearly every ball in the barrel, but I think it was mostly because he never cleaned his stuff. He eventually traded the Spyder and $120 to his bro for a Mag. I was cleaning it up later on and discovered a 1" crack on the inside of the middle section. Dunno if it was causing the breaks or not, but the fact that he didn't know it was there says sumpin' 'bout his gear care habits.