The following are my personal favourites and they are all synthetic stones, I do have experience with natural what stones but lets keep it simple, lets stick to synthetic water stones. Believe me, some of the world sharpest knives are sharpened solely on synthetic stones. Here are my personal favourites, I use these water stones every day and the order is not necessarily in priority, they are all good.
I can personally verify that this will get your knives very sharp. I will spare you all the gory details, but the picture is of the instructions the ER sent me home with after stopping the bleeding and patching me up. I have to say, that’s not what I had in mind regarding “Thanksgiving tips”. So: not only will knives slide easily through spinach, but they will go through finger and fingernail like a hot knife through butter after being sharpened by this whetstone. Very clean, straight cut. Impressive, really. Just take it slow and don’t be a moron like me.

This was the first Whetstone that I've ever purchased. After reviewing several 'how-to' videos, I jumped right in to use it. I found the process nearly meditative and the BearMoo stone extremely effective! The first knife I sharpened was very dull with small, jagged edges. The 1000 grit side effectively removed the jagged indentations and created a nice cutting edge. The 4000 grit side made the knife razor sharp. The process took nearly 40-minutes.
The type and size of the blade being sharpened determines the size of the stone needed. In general , a 6" stone is considered a small sharpening stone, an 8" stone is a common larger size, and a stone larger than 8" (10"-12" are available) is considered generously sized. Stones smaller than 6" (3" and 4" stones are quite common), are considered pocket stones and can be used for toolboxes, tackle boxes and on-the-go sharpening, but are generally not recommended for regular sharpening jobs. 

You will be given access to our useful online learning material: a set of videos and articles to help you improve your sharpening technique. These resources were made by professional knife sharpeners, specifically for beginners and intermediate sharpeners. The articles and videos will guide you and teach you knife sharpening from scratch, also covering more advanced techniques. You can also get in touch with us anytime if you have any questions concerning sharpening specific types knives.
Clamp-style sharpening tools use a clamp with several holes with predefined angles. The stone is mounted on a rod and is pulled through these holes, so that the angle remains consistent. Another system is the crock stick setup, where two sticks are put into a plastic or wooden base to form a V shape. When the knife is pulled up the V, the angle is held so long as the blade is held perpendicular to the base. Several cutlery manufacturers now offer electric knife sharpeners with multiple stages with at least one grinding stage. These electric sharpeners are typically used in the kitchen but have the ability to sharpen blades such as pocket or tactical knives. The main benefit of using an electric sharpener is speed with many models that can complete the sharpening process in one to two minutes. The disadvantage is that the sharpening angle is fixed so some specialized knives, like a Japanese style Santoku, may need additional attention to sharpen to the ideal angle. 

However, due to limited natural deposits and extensive quarrying over the centuries, true, high quality, Japanese water stones are now few and far between and are very expensive. Thus, various companies are now producing synthetic Japanese Water Stones which generally have a more consistent composition and grit size than natural stones as well as often begin somewhat harder and thus, lasting a bit longer; not to mention being cheaper to purchase.
My first set of sharpening stones so I have nothing to compare them to. For $50, though, great price to get into the world of sharpening. Stones are great and easy to use. Was able to put hair shaving edges on knives. Took a couple of knives to feel comfortable and better with the process and how to sharpen, but the stones you get work great. Here's the secret though. Get the green leather stoping block as well. As great as the stone are, I have found that stroping the knife after the fact is what really brings out that razor edge. And after using the knife, stroping it again, will restore and keep it razor sharp. Hope you enjoy it as much as I am.