I love my Sizzix for cutting chipboard. My Pazzle will cut it, but you have to adjust it. It is just easier to use my Big Kick. However,if I don't have a Sizzix die for what I want then I will use the Pazzle.
Definately Sizzix although Cricut is coming out with a deeper blade housing which is going to be able to cut through thicker materials like chipboard. I'm really curious to see how that is going to work before I go out and buy it.