It all depends on how much you want to spend (time-wise and speaking monetarily) - you can go all-out and invest in a 2" belt sanding setup that'll allow you to do everything from flat grinds to convex edges relatively quickly or you can get something like the Spyderco Sharpmaker (awesome rig). The Sharpmaker is an example of a "Hold the knife vertically and push it down" system.
You can also go with Lansky/DMT systems, straight-up benchstones (Arkansas, waterstones, or india stones) or even incorporate a strop.
Typically those on the back of kitchen products are good at one thing: overheating a knife and ruining its temper. It will also usually completely destroy any blade geometry. The sharpener may induce a slicing edge (one that appears like a saw under a microscope) but it will likely not be a good angle for the blade's intended function.
My suggestion, hit up
http://bladeforums.com or
http://knifeforums.com and look around a bit and ask your questions there. If you prefer to get down'n'dirty with your research, google is always a viable option.
Feel free to PM me if you need more depth in this topic.