I sharpen woodworking tools so my point of view is slightly different, but I'd recommend diamond plates over water stones.
I've had great results with both but water stones need to be soaked in water before use (instructions say 10 minutes, but my experience is more like 30 minutes), they release a messy slurry when they wear and they don't stay flat for very long (flatness isn't that much of an issue with knifes I suppose, but essential for woodworking tools) and wear down as you use and re-flatten them.
Diamond plates stay dead flat, need very little maintenance, ready to use (just wet them, no soaking) and last 10 years or more in my infrequent use.
1200 grit isn't super fine (compared to water stones) but is enough for basic kitchen sharpening (you don't need coarser ones unless you sharpen damaged blades and you don't need a finer one to get decent sharpness). I'd add a leather strop and some honing compound (chromium oxide) if I needed to get them sharp enough to shave (like I do with my tools).
That's about $20 for diamond plate + strop + compound, you can't get a decent water stone for that price.
But the real difference between sharp and kinda-sharp is practicing the skill of honing the blade. Sharpen a little at a time, test frequently and do it often.
I've had great results with both but water stones need to be soaked in water before use (instructions say 10 minutes, but my experience is more like 30 minutes), they release a messy slurry when they wear and they don't stay flat for very long (flatness isn't that much of an issue with knifes I suppose, but essential for woodworking tools) and wear down as you use and re-flatten them.
Diamond plates stay dead flat, need very little maintenance, ready to use (just wet them, no soaking) and last 10 years or more in my infrequent use.
I have big 8" plates for my woodworking tools, but I intend to buy a small 1200 grit sharpener for kitchen for about $6 from here: https://www.fine-tools.com/ezelap-diasharpener.html
1200 grit isn't super fine (compared to water stones) but is enough for basic kitchen sharpening (you don't need coarser ones unless you sharpen damaged blades and you don't need a finer one to get decent sharpness). I'd add a leather strop and some honing compound (chromium oxide) if I needed to get them sharp enough to shave (like I do with my tools).
That's about $20 for diamond plate + strop + compound, you can't get a decent water stone for that price.
But the real difference between sharp and kinda-sharp is practicing the skill of honing the blade. Sharpen a little at a time, test frequently and do it often.