There are quite a few good ones to choose from. My personal favorite for a hard use knife is CPM 3V. I have knives with 3 inch blades all the way up to a 22 inch slimline machete. They all perform great, and the larger ones get beat to crap about every day, and take it like champs. You can see my 22 inch blade machete in my profile picture, along with a few other 3V fixed blades I have. It has great toughness, edge holding, edge stability and durability, corrosion resistance. Just a great all around steel! Another very close runner up, much closer to the other mentioned below would be CTS-PD#1, CPM Cru-Wear, Z-Wear. Those three are all basically the same steel. They somewhat similar to 3V, and are also very well rounded. Another would be Z-Finit. I got a knife in this a few months ago and it is very impressive! That is a Nitrogen Stainless, with very good toughness!
There are other good steels, countless good choices, but IMHO they are not as well rounded as 3V. Others would be AEB L/13C26, A2, L6, O1, 80CrV2, 5160, Cru Forge V, etc.
But, other factors that are just as or more important are. Heat Treatment and blade geometry.