I have both sahrpeners. The Sharpmaker wil let you put a great edge on your high-end kitchen knives. I use it to sharpen my Shun and Henckels knives.
The chef's choice will put a decent edge on a knife, but I wouldn't use it on any high-end knife. I mainly use it to sharpen my cheap-o low-end kitchen knives. It is a lot faster than a Sharpmaker, and I feel like I would be wasting my time putting a great edge on an OK, cheap-o knife.
So, in summary - Sharpmaker = great for sharpening high-end knives
Chef's choice - very good for sharpening low-end knives