I've tried several.
Edge Pro's probably the best but expensive.
WartHog's good but scratches the blade if ya don't tape it up.
I bought a set of paper wheels recently that are fantastic once I got the angle figured out. (Kinda tricky with a round cutting surface).
The paper wheels are a real value and fast as all get out, but for my old favorites I still go back to my old Arky stones.
One caveat. No body's mentioned the difference in flat ground and convex ground blades.
I dang near ruined a nice little S&M Muskrat before I learned myself how to sharpen a convex blade. Once I did, I actually prefer that grind. Pretty sure the old leather razor strops were designed for em.
I use a soft mouse pad (one of the old ones), start with 600 grit sandpaper and work my up to 2000.
There's a great video on the knivesshipfree website for those that haven't dealt with convex blades. (like me)
One thing's certain though. No matter which tool or method you use, untill you get the angle right, you're just rubbing.

I took a couple pix of my "gadgets" but PhotoBucket's giving me grief.
I'll try and post em tomorrow.