What steels are best for all-round knife making (i.e. not for any special applications)?
Carbon steels, 420C, 440C, VG10, RWL34, Damasteel... There are a lot of options.
Looks like there was already an answer here, but there are a lot of variables not considered:
If you are going to send out your blades for heat-treatment, then any steel with medium carbide volume is going to be fine. These include the simple carbon steels, from 1070-1095, O1, A2 as well as stainless steels like AEB-L (Sandvik 13c26), CPM-154, S35VN. Note that CPM-154 and S35VN are both higher carbide volume, but made with a powdered metallurgy process, which reduces the disadvantages of high carbide volume. I would avoid the super wear-resistant or ultra-tough steels, as they are more specialized and you've asked about general use knives.
For most people who don't want to maintain carbon steel, I'd recommend CPM-154 or S35VN. If you're going to the trouble to MAKE a knife, don't start with performance and market-limiting blade steels like the 420 series or 440C. Yes, you can make a very good knife with them, but you're starting with an unnecessary disadvantage only to save a few dollars in material. Most of the cost of a custom knife is labor.
For carbon steels, I'd recommend 1084 if heat-treating at home for stock-removal blades, and 80CrV2 if forging at home.
The poster below makes some good points - I answered with steels available in North America. Steels available in Europe and elsewhere will be different. I believe RWL34 is very similar to CPM-154 (or is it 154CM? powered or not is the difference).
I've spent months on ocean-going ships with my 154CM blades (that I made), and no corrosion problems. Of course I wasn't processing fish in the Bering sea... A small amount of maintenance will go a long way. Just keep it clean and put it away dry. If corrosion-resistance is a priority, be sure to use (or specify) the lower tempering range, not the secondary higher range, which reduces corrosion-resistance in many high-alloy steels. Nitrogen-heavy steels win in this category, but some (like H1) are not hardened in the traditional manner, and may be harder to manage for the home craftsperson.
Mine would go to Sandvik 14C28N, Nitrocut NCV60 or similar steels with medium Carbon content and >0,1 Nitrogen. Always taken for a high quality manufacturer because chemical composition is far from making the quality of a steel alone.
Relatively stainless in most environments except sea or underwater. Lower maintenance than Carbon Steel and safer for food contact.
Easy to sharpen. Gives a fine edge thanks to Nitrogen. Holds quite well an edge.
Quite low prices given the quality level.
Of course a powder metallurgy RWL34 and others very high hardness steels will hold and edge longer. But this is a lot of cost for a small performance improvement. It is also harder to resharp.
If I have to work on a boat or going into rivers these steels will not do the job for long. Knife steels rust very fast. I would go to modified versions with >0,2 Nitrogen and >1 Molybdenum. Bohler N680 is a good reference. This type of steel is also a good option for food contact intensive uses like chief knives.