This is solely based on my experience as a peacetime infantry Marine, the most combat I've seen is two marines duking it out in the tree line after dark and the closest I've come to being shot at is pulling pits for marines qualifying on the range, so take it for what it is.
Money is no object: Winkler or (possibly) Bark River, I've carried a Bravo 1 3v, a Gunny 3v and a Bushcraft Scout Magnacut on my gun belt. The micarta handles do seem to get a bit uneven with the tang when they soak and the temperature dips below freezing, but no real functional issues to speak of. The leather sheaths they come with make me nervous retention wise, especially in the rain and someone expecting to see combat would probably have to buy a good kydex sheath second hand for that durability and retention. I just got a Winkler woodsman and based on my limited experience with it, I feel that as a military (not bushcraft like a bark river mind you) knife, it probably would be my ultimate utility knife of choice, I'm yet to see how it holds up when it's pissing rain on me for days at a time, but if the old breed of marines carried their 1095 Ka-Bar's through the Pacific Jungles, I'm sure the 80CrV2 found in my winkler will hold up just fine with a little bit of care in the field. The way it is built feels indestructible while also not feeling like a sharpened prybar. The sculpted handle and the texturing of the micarta ensure a locked in grip no matter what wet and slippery substance is on your handle, which crucially the polished (and admittedly extremely comfortable) bark river handles don't really have, I also find myself worrying about scratching up that nice polished bark river handle, a worry I just don't have with my winkler. The coating on my winkler is excellent and does not wear easily, it is incredibly easy to make stupid sharp in a very quick manner, and it seems to hold a working edge almost as well as some of my knives in CPM-3V. Hitting the edge on a stone countertop by accident only left the tiniest microchip that sharpened out in about 30 strokes either side on a 400 then 800 grit diamond stone. the only real downside is the poor stain resistance but the excellent coating really minimizes that as a worry. It also comes with the best sheath I have ever owned with excellent retention, so it's another plus that I can just put it on my belt out the box and go.
For the financially literate: Esee 4, all the way. Maybe if they have a version of it without the choil, as the small handle and large choil feel awkward balance wise, but it's just the perfect size for a utility knife made by a rock solid company with a good heat treatment that will replace it no questions asked when it is inevitably broken by a grunt doing some stupid shit, all for ~$100. It also comes with a good sheath right off the bat, Esee knives really do feel like Winklers in terms of use case just without all the frills, well heat treated simple steel that is damn near indestructible and was made to bet your life on.
For a folder: I'd take my Benchmade mini-adamas, it's construction is nice and open and there's not nooks or crannies for dirt and grit to get stuck, the less complex the lock up system the better, that being said I will always recommend an infantryman to have a fixed blade over a folder. Since it is so light and low profile, I am playing with the idea of taking out my microtech UTX-85 on a field OP after having seen some YouTube torture tests on it where it stood up to an almost unbelievable amount of abuse, I'm talking throwing into the ground full force, running it over, batonning, and shooting the edge straight on with .45 acp with no chipping or deformation visible on the edge afterwards. I would love to see how it does as a secondary knife but I feel it would get gunked up real quick with sand and mud and very quickly become useless.
Multitool: My leatherman OHT any day of the week, It can easily be opened quickly and one handed which is huge with certain tasks, I use the flathead screwdrivers as scrapers to clean carbon out of the machine guns, the replaceable wire cutter along with the pliers are arguably the most useful parts of the leatherman and have a million different uses, it has a little threaded hole I can screw a cleaning rod into if I need an emergency T-handle, it is coated so it doesn't rust up too bad, it has a nice saw and serrated blade to help with some real basic fieldcraft, and a knife I don't care about to lend out to the same fuckers that always ask why I "need" to be carrying a knife on my belt. I have carried the thing for a year and despite the kind of rattly construction it appeared to have upon first inspection and being all dinged up over the past year, it has proven to be one of my most reliable and used pieces of personal kit, it oulasted my Gerber multitool, which rusted quick and some idiot managed to break the tip off the pliers after I'd had it for about a month, granted you may not be an idiot to snap the tip off some pliers, but in the military you have to consider you will sometimes have to lend your gear to a fucking idiot, no one as of yet has managed to break my leatherman.
Their old SK5 knives I mean, not these new crazy GSM knives selling $10,000 4034 knives with plastic scales.
