How many knives will you actually be sharpening, and how often do you need to actually remove metal? How much space in your home would you dedicate to sharpening?
If the answers to the first question is just 3-4 knives to sharpen a couple of times a year, then most powered systems are pretty much a waste of money. Knife use like this requires infrequent sharpening combined with frequent touch-ups. Other wise you will wind up grinding away your blade in a just a couple of years. I sharpen my knives 2-3 times a year using an EdgePro or DMT Aligner clamp. The rest of the time the blades get weekly touch-ups on a Sharpmaker, the kitchen knives also get steeled between uses. These are very portable units, can be stored in a drawer between uses, and set up in a minute or two.
If you have dozens of knives, or need to sharpen knives every day for business purposes, and have a workshop to set them up, a machine device such as WorkSharp, Tormek, and belt sanders are effective, as are paper wheels.
"ALL" the sharpeners work, some faster, some more accurately. Plan your sharpener purchase based on YOUR own need, rather than someone else's.
Stitchawl