Blade compatibility: Check the listed blade types before choosing. The Chef's Choice 15XV and AnySharp GLOBAL specify straight-edge and serrated knives. The WORK SHARP Professional Precision Adjust lists pen, pocket, hunting, fillet, and kitchen knives. The Ken Onion Elite Mk2 also lists scissors and garden tools, but its wider use range comes with an electric belt-sharpener format.
Angle control: If you want a choice of sharpening angles, compare the WORK SHARP Professional Precision Adjust, which adjusts from 15° to 30°, the HORL 3, with 15° and 20° options, and the Ken Onion Elite Mk2, which adjusts from 10° to 35°. The AnySharp listing states a preset 20° angle. The Chef's Choice 15XV specifies 15°. These are different approaches, so consider whether you prefer a fixed angle or a stated range.
Format and user control: The Chef's Choice 15XV is electric, while the AnySharp GLOBAL and HORL 3 are manual options. The Wüsthof whetstone has 1000/3000 grit, but manual stone sharpening requires angle control. Choose a guided format if you want the sharpener to help set the blade path; choose the stone if you are comfortable controlling the angle yourself.
Space and setup: The HORL 3 listing gives product dimensions of 2.6 x 5.2 x 4.7 in. The Wüsthof stone measures 1.2 x 7.9 x 2.4 in. Compare those listed sizes with your storage space, and note that a compact stone still calls for hands-on blade control.
For practical advice, see How to Use a Guided Clamp Knife Sharpener.