I gave up using the GP spinners long ago due to them breaking at the center, it was probably me over tightening them but the only ones I have broken were the GP spinners. My LHS started selling the Magnum spinners and when they came out they were a bunch cheaper so I started using them. Now there isn't a big price difference but I haven't bought a new spinner in a few years. I still have several of them I keep using.
The quality of the Magnum is as good as any.