DMT duo-sharp bench stone. 8"x3". Fine/X-Fine.. buy the stone holder. That's the 'down the middle' sharpener that will do a fast clean job on any ordinary/average sized knife.
It's not enough by itself to do everything but it'll sharpen MANY things very rapidly to a using level..
A slightly cheaper solution is a Norton Waterstone (combo) of 1000-4000 grit, 'entry level' stone that still works well..
My recommendation is to use either a dry (DMT/EZ-Lap/Other) diamond hone, OR mid-grade or better waterstones.. don't try to learn both at the same time. The dry stone will give you a slightly coarser and toothier edge, which may be perfect for your needs.
The waterstone gives (in general) a more polished and aligned edge, generally suited for lighter cutting and more controlled enviornments. (kitchen work)..
You can find small tools and jigs that'll allow you a good result on ONE knife.. or you can buy the tool and grow the skill that lets you sharpen anything. . and you'll likely gain patience in the process as well as skill. I would think a minimal stone collection would have a dozen stones perhaps. . and cost a few hundred dollars.. but a full suite of stones will do everything from lawn mower blades to a straight razor. Get a good bench stone to start, add in small specialty hones as you find you need them.. most decent sharpening tools will last many years and possibly outlive you, so choose carefully..
