I prefer Victorinox but I think that is just a familiarity thing. I think I'd probably build a preference between Forschner and Swibo in the kitchen too, based on nothing more rational than mere exposure.
I know Victorinox landed the first contract, but that wasn't by much. I can't give a source but I have it on good authority that the military has subsequently been meticulous in drawing 50% - 50% of its stock between the two companies.
My first SAKs were Victorinox, so I guess they set the template of what a SAK should look like. Then I owned some Wengers. Although the blades were the same on them they had those more kinda burgundy mother-of-toilet-seat looking scales. That was a bit of a turn off I'm guessing a] because they didn't match the template of the first ones, and b] was a colour more akin to that which el cheapo skanky ones come in. In sum; familiarity and guilt by colour association not a good way for me to evaluate a knife but a nag none the less.
More reasonably; my first locking SAK was a small Wenger. It was the first locking SAK I'd ever seen. Loved it, toted it a lot.
Just to wind another angle in: I've owned a couple of German Mauser officers knives. They were the first big SAK type things I had. A couple were Victorinox and one of them was an Aitor. I've never held Aitor in high regard but I have to say on those Mauser knives the quality between a Victorinox one and an Aitor one is indistinguishable to me.
For now my favourite SAK happens to be Victorinox, and that is handy because I don't need to check my reasoning circuits for nags and errors. If Wenger builds something I like even better than the Outrider I'll switch.
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As we are here it's worth noting that Mauser officers knives turn up in surplus shops usually priced at 2 for the cost of a gallon of gas when the scales are cracked. Under the scales is a very functional little knife if you have the skill to put new scales on, [epoxy and wood, bone, micarta, blah blah how hard can it be] Look for the ones that also have the pen blade, most have only the spear.