This is an amazingly complex subject, with all manner of lore, not to mention gadgets you can buy. You can sharpen free hand, but most people are best served with some kind of jig to maintain a constant angle. There seem to be 3 levels of skill in knife sharpening:
Another product is "Tuff glide". You can also get "Tuf cloth" to go with it. This is marketed as a lubricant, but its real virtue is corrosion protection. Use Nano-oil or Tri-flow on the pivot.
The Lansky has been around a long time and is available in department stores. For one reason or other it does not seem to be favored much these days and I will say no more about it.
The Wicked Edge is wickedly expensive. That is probably all you need to know and all I need to know to move on. It requires you to have two "stones" of each grit, doubling the cost of adding any capability. It might have merit if you are some kind of commercial high-volume sharpening service. Maybe.
So this leaves us with the Edge Pro versus the KME. These are both well regarded by serious knife freaks. The KME has a clamp to hold the knife. The Edge Pro requires you to hold the knife against a rest. Both are jig systems that sharpen at controlled angles. I am hearing more good things about the KME.
Tom's Knife Info / firstname.lastname@example.org