I have been sharpening knives ever since I was about 10 years old. In the beginning I took a dull knife and made it even duller using a silicone carbide stone - or similar! lol! After I got married 46 years ago I bought a Lansky (or similar) system. Years later I bought the KME system which IMHO is way better, gave me great results but took way too long for each knife and replacement stones are costly. I then bought the Spyderco system and while it works well, it is basically only good for slightly dull knives. Start with a really dull knife and you will be there all day long! Along the way, (about 38 years ago) I purchased a really good set of 3 Arkansas Stones. Again, they can give great results if you have the muscle memory to hold a consistent angle, but take a while if doing multiple knives. They are also a bit more messy as I used them with honing oil.
A few years ago I decided to get serious about sharpening and I needed a method to sharpen knives fast and at the same time be able to make them razor sharp if I want to (depending on what knife I am sharpening). At the urging of StrawHat here on the forum, I bought a bunch of larger diamond stones (3" x 8" and 3" x 10") in different grits. Since buying them I have done many hundreds of knives, scissors, chisels, etc and they are IMO the absolute best way to go. The diamond stones last a very long time too! Someone doing sharpening just on their own personal knives will probably get decades out of quality diamond stones. A 325 - 350 grit and a 1200 grit are the two (course an fine) stones I'd get. Finishing the process with a good leather strop and that is all you will need IMO.
Learning to hold a consistent angle is way more important that the actual degree of angle you sharpen to. Anywheres around 15º-20º is good and 17º is what I sort of shoot for but never really check. For fine cutting knives I will lean towards the 15º and for your average knife about 17-18º. If the knife is a shop knife subject to rough work, I will even increase the angle a bit more to 22º - 25º, but again, I no longer measure the exact angle - I just go by feel now. The key is develop muscle memory to hold the angle consistent. There is no magic bullet other than to keep practicing, use your thumb and forefinger as an angle guide, and use a magnifying lens to make sure you are getting one consistent angle instead of many different facets.
I can usually sharpen a dull kitchen knife in about 7-10 minutes (including stropping). One that has been really abused and neglected and needs re-profiling obviously will take me longer - about 15 minutes. I know many can do it faster, but probably not better. When I sharpen a knife, I sharpen it to what it will be used for.
I know some buy the Worksharp products (a bit pricey to buy and get belts and parts for) but I personally do not like using a glorified motorized belt sander on fine knives. Sometimes I will use a belt sander to rough profile a knife that is in really poor shape and needs to be thinned a little. I then finish by hand on the diamond stones. Yes it can be quicker but most who use them exclusively more than likely cut the longevity of the knife down by removing too much metal each time it gets sharpened. On my own personal knives I never let them get really dull and I can put a razor sharp edge back on them in 30 - 45 seconds just with the diamond stone. A few licks on the strop and the sharpened knife is back in the block in a minute. Hand sharpening is a developed skill that many can do if they are determined. Some just want the easy way out. Whatever method or sharpening system you use needs to satisfy your needs, skill level, pocketbook and patience level. BTW, a diamond stone needs no real maintenance, requires no electricity, oil or water so it can be used anywhere.
