Kitchen knives generate an enormous amount of discussion relative to how simple the requirements are. Most of what determines whether a knife works well is not what gets debated.
Sharpness dominates everything
The single most important factor, ahead of steel type, brand, construction and price.
A cheap knife that's sharp cuts better than an expensive one that's dull. This isn't close.
Most home knives are dull. People generally don't realise, because sharpness declines gradually and you adapt without noticing. The comparison only becomes obvious when you use something genuinely sharp.
Dull knives are also more dangerous. They require more force, they slip off food rather than biting into it, and the injuries that result are worse than those from sharp knives, which tend to be clean and shallow.
Honing versus sharpening
Two different operations that get confused, which is why a lot of people think they maintain their knives and don't.
Honing, with a steel rod, realigns the edge. Cutting causes the very fine edge to bend microscopically, and honing straightens it. This restores cutting performance temporarily and removes essentially no metal.
Done frequently — every few uses — it keeps a knife performing well for much longer.
Sharpening removes metal to create a new edge. Necessary when honing no longer restores performance, typically every few months for a home cook.
Somebody using a honing steel and wondering why their knife never gets sharp is doing the right thing for the wrong problem.
Sharpening options
Whetstones. Best results, most control, steepest learning curve. A combination stone with a coarse and fine side handles most needs. The skill is maintaining a consistent angle, which takes practice.
Guided systems. Hold the angle for you. Good results with less skill, more expensive, slower.
Pull-through sharpeners. Convenient, and the cheap ones with carbide scrapers remove metal aggressively and produce a poor edge. Better than a dull knife, worse than anything else.
Professional sharpening. Available in most places, inexpensive, and entirely reasonable if you don't want to learn. Once or twice a year for a home cook.
How many you need
Fewer than any knife block contains.
A chef's knife or equivalent. Does eighty percent of the work. Size is personal preference — a shorter blade is more manoeuvrable, a longer one handles large items better.
A paring knife. Small tasks, peeling, anything in the hand rather than on a board.
A serrated knife. Bread, tomatoes, anything with a tough exterior and soft interior. These can't practically be sharpened at home and are eventually replaced, which argues for a cheap one.
That's it for most cooking. Everything else is specialised and worth buying only if you do the specific task regularly.
The knife block full of matching knives is a marketing format. Most of them are never used.
Types worth knowing about
Beyond the Western chef's knife, several designs suit different cutting styles.
Japanese-style knives are generally harder steel, thinner and sharper, holding an edge longer and being more prone to chipping. They're typically sharpened at a narrower angle.
The nakiri, a straight-edged vegetable knife, suits a push-cutting motion and is excellent for anyone who does a lot of vegetable preparation.
The santoku, a general-purpose Japanese design, is shorter and flatter than a Western chef's knife and suits a different technique — less rocking, more up-and-down.
Which suits you depends on how you cut, and that's worth establishing before spending money.
What actually matters when buying
How it feels in your hand. Balance, handle shape and weight are personal and cannot be assessed from a description. Holding it matters more than any specification.
Whether you'll maintain it. A very hard steel that holds an edge brilliantly is difficult to sharpen at home. A softer steel dulls faster and is easy to bring back. Match the knife to your willingness to maintain it.
Thickness behind the edge. A thin blade cuts with less resistance. This matters more than the steel and is rarely specified.
What matters less: brand, the country of manufacture, full tang construction for home use, and the number of layers in a pattern-welded blade, which is decorative.
Looking after them
Simple rules that make a substantial difference.
Wash by hand and dry immediately. Dishwashers damage edges through contact with other items and degrade handles.
Use a wooden or plastic board. Glass, stone and ceramic boards destroy edges rapidly.
Don't leave them in a sink, where they'll be knocked and where somebody will reach in and find them the hard way.
Store so the edge doesn't contact anything — a block, a magnetic strip, or an edge guard. A drawer full of loose knives is bad for the knives and bad for your fingers.
And use the right knife for the job. Chef's knives are not for hacking through bone, prying, or opening packaging, all of which will chip an edge that took twenty minutes to put on.