I have had an STS-5 for a while now. It's like a Camillus CQB1 and an ESEE-5 had a baby, and then that baby was better than both of the parents put together.
It's a thick bladed beast of a knife, but it balances perfectly so it doesn't have the awful "sharpened pry bar" feel of the ESEE-5. The convex edge gets sharp and stays that way through use. The knife is made from 154CM, so it won't rust easily and will hold an edge. The handle, at least my G10 version, has a very unique "scoop" out of the front of the handle which makes the knife "self righting" in my hand, meaning that no matter how I pick it up my hand will readjust the blade to the proper position. The palm swells and grip profile is perfect either blade forward or in a reverse grip. Even though it's almost a quarter inch thick, the handle slabs are super thin (which is why there are no wood grips available) so the overall profile is very slim.
The STS-5 is the best compromise between a "user" and a "fighter" that I've ever come across. It really is good at everything from processing wood for a fire to doing high speed Kali drills.
DLT sells an STS-5 sheath with a unique locking mechanism to hold the knife in. It's all leather, but wraps around the grip and you push the "button" to release the knife. This unique sheath is a great reason to get the STS-5.
I made my own kydex sheath for the STS-5, which was super difficult due to the square piece at the base of the blade. It took me several tries, but I got it perfect. I'll post some pictures tomorrow morning.
