For super tough and takes a great edge, there are relatively few choices. These are the ones I can think of in order of worst to best edge holding potential and generally from least expensive to most.
4340 or 4140
both low alloy steels with medium carbon, both very tough and will take a sharp edge. Edge holding will be less than the other steels listed. These are also basically limited to custom knives from understanding makers, since almost no one uses them except by request. Hardness, which is pretty much the only way they have edge holding ability, is mid to low 50's on the Rockwell C scale at maximum.
5160,9260,1055,1060
all low alloy steels or plain carbon steels with 0.5 to 0.6 percent carbon by weight. Higher hardness, better edge holding and slightly less toughness. All these listed are commonly used for swords, so the drop in toughness is minimal. 9260 is probably the toughest out of the group and second in edge holding to 5160 by most reports, though I've never used either so I cant comment with certainty. These are slightly more expensive than the last group, though prices will vary and they can be the same or even cheaper. These are more commonly used for knives, with 9260 being the hardest to get. They are also easier to find in stock sizes suitable for knives.
8670, 1075, 1080, W1, W2, 1095
low alloy, plain carbon, and in the case of W1 and W2, tool steels. Listed in order of decreasing toughness, but very dependent on heat treatment. Edge holding will range from good to excellent. This group and the above group are commonly given heat treatments with soft spines and hard edges, increasing overall toughness to tremendous levels, but the edge can still crack. Also still relatively inexpensive, and much more common in production knives.
O1, A2, D2, A8, L6, S7, S5, CPM 3V
all tool steels with specific needs in mind for the formulation. 3V is generally regarded as the best of this group, but is much more expensive. S7 and S5 are formulated specifically to resist impact and are used for pneumatic tool bits. L6 is very tough, while giving good edge holding potential. O1, A2, and D2 are quite common, with lesser toughness than the others listed here, but potentially greater edge holding ability. These are all very dependent on heat treatment. Toughness generally increases as carbon content goes down, with S7 and S5 having the lowest of the group. However, there are some pics on the makers forums of some O1 blades hardened from edge to spine that took 90 degree bends without breaking. O1, L6, and S5 can be heat treated with a soft spine and hard edge, making the 90 degree bend easier to take without breaking.
The reason for the cold reception was that there are literally thousands of steels available, and probably hundreds that could be used for knives. I've listed 20 here and have barely scratched the surface. None of the above are stainless, so I've left out an entire category. CPM steels are proprietary and relatively new, and each steel company has its own version for similar uses, and new ones are being formulated as we type. Heat treatment plays a huge role in toughness and can be very simple or very complicated, on the same steel, to say nothing of different steels. Just thought you'd want to know the barrel of worms you opened. I would suggest further reading in something like the Metals Handbook if you're interested, as most of the knife steel charts I've seen on the internet and in some books are oversimplified to the point of being misleading.
Of course, after reading this you could just be shaking your head and trying to uncross your eyes, so I'll offer a simple solution based on your fixed blade, tough and sharp outdoor knife criteria. Blade shape, size, and handle design are all important, but you asked only about steel, so here you go. Get some 1095, 5160, or O1. 1095 is easy to get in production knives and has huge variety. 5160 is harder to find, as is O1, and they will be more expensive.
