Your question is like asking, "What's the best way for me to get to work?" You'd get answers from bicycle to commuter train, 'cause there's no way of knowing without more information. Most "gadgets" work to some degree, and most of the answers you get or will get will sharpen a knife. You need to provide more information like: how much do you want to spend, power or manual, how long you want to spend sharpening a knife, how much time are you willing to invest learning, where you will sharpen, to name a few.
The main categories are:
Freehand: no "gadgets" here, just deciding the type of stones to buy, and the time to learn.
Guided: Lansky/Gatco, Sharpmaker, KME, Edge Pro, Wicked Edge, etc. The decisions here are mostly cost, and the time it takes to get a knife sharp.
Powered: Sharpening Wheels, Belt Sander, Tormek, Work Sharp Knife Sharpener, etc. Again, cost, time, etc. will narrow it down.
To help decide, take a look at the
Sharpening Made Easy website, it will give you a basic idea of how various sharpeners work.
Or buy this...
... and you could start a business.

(Just wanted an excuse to post this picture)
Edit: p.s. there's no "miracle" gadget, no matter what you choose, you should take the time to learn what it takes to properly sharpen a knife.