Things to consider when choosing a knife sharpener
What kind of precision and sharpness do you require?
If your knife is to be used to open boxes at work and a quick touch-up on the edge once a week is reasonable, then a bench stone for hand held sharpening may be the perfect choice. But if your hunting knife is going to be asked to clean an entire elk in the remote high country where sharpeners are non-existent and a pocket stone simply cannot do the job, a knife sharpening system that can make a precise edge bevel leaving a precise razor’s edge before the hunt is necessary(along with a very hard, high grade tool steel blade). A straight razor needs a nearly perfect fine angled bevel and very smooth edge so as to make for a smooth clean shave. In this case whatever stones that are used should be able to sharpen at a very fine grit finish, perhaps 15,000 or even 30,000 grit. The more rugged clamping system such as Wicked Edge have the upper hand in precision simply because the blade is solidly held while it is honed. Hand held stones are the worst for precision because it is impossible to maintain precision while sharpening by hand. That said, they may be good enough for certain uses you may have. Of course there are many in between.
What kind of steel are your knives made from?
Generally the steel is chosen to match the job, stainless in the kitchen to avoid rusting of constantly wet blade, tool steel in knives that need to take a lot of abuse. The high quality stainless and tool steels used today can only be sharpened by high quality stones. I prefer diamond stones and strops coated with diamond paste. Some of the man made stones on the market are very soft and cannot remove metal on higher grade tool steels. Others (Shapton and others) are of such fine quality they do an excellent job of putting the very finest edge on any type of steel blade.
What is the blade used for?
Similar to the first segment above. If your blade is used in shipping and receiving, hunting, cooking or chopping the quality of the edge must match your needs.
How big is your blade?
some sharpeners can only do blades up to say 12” well. These generally clamp the blade in a vise and stroke the edge bevel with guided stones. The maximum length of the blade sharpened is related to the length of the stone guides. Think Lansky or Wicked Edge. Others allow for the blade to be relatively stable while allowing it to slide across the sharpener as the edge is refined. Think Edge Pro.
Is your blade double edged or tapering from handle to the tip?
As in very long knives the non-clamping styles are more effective here. The clamps have some trouble centering and holding sufficiently to allow sharpening without shifting the angle of the blade. The clamps excel on knives with parallel faces. The the non-clamping Edge Pro is likely best for tapering and double edged blades.
Convenience of use:
A casual box cutter touched up weekly on a bench stone is the classic example of convenience. Other contraptions can be so complicated to utilize they are not useful. The Wicked Edge while seemingly complicated is very simple to use. Mine is mounted on a plywood base with facility for hanging the entire system (stones included) on a wall in my shop. If I need to sharpen a blade all I need do is take it down and clamp the blade in place.
Price:
You should consider it worthwhile to spend the most you can afford in the class of products that best meet your needs. A Boy Scout with his jigged bone friction folding knife may only be able to afford a combination coarse and fine grit bench stone. As your budget grows so will your collection of the worlds most useful tools, knives and cutlery! Do not forget to upgrade your sharpening tools as well. A knife is simply a letter opener unless it is sharp.
Someone once said, “Only sharp knives are interesting!”
In conclusion, the knife sharpener or knife sharpening system you choose must match as closely as possible your needs as described above. Unlimited budgets are rare, but they make things easy. If you rely on your cutlery for your work; spending more is definitely in order. If your collection includes many longer bowies, kukris and even swords, then a non clamping system such as the Edge Pro Apex may be the best choice. For kitchen knives, EDC blades and most “general use” knives a clamping system is in order. If you can afford it The Wicked Edge is a terrific all around sharpener. Take your time, analyze your needs and make sure your purchase can do what you need it to. No matter how good it is, if it not easy to get out, use and put away it wont be very useful. You’ll have another item to store.