Which of these two do you prefer, without suggesting alternatives. Just these two. Like they are the last 2 on earth.

I suggest you open your horizons, they aren't the last two on earth.  Preferring leather and one with replaceable clips and priced in between those two I'd look at Ronin Leather Holsters, Aegis model.   That said, the Tulster Oath provides a better value and would likely conceal better than their Profile model.

Never heard of the Kusiak, but I bought a Tulster P365XL holster off Amazon and it was the POS that you’d expect a $40 holster to be and I should have known better. If you don’t want to wait for a custom just get a G-code incog, it’s an excellent holster and more than worth the little extra $$ for the comfort and quality you get.

My friend gave me a g-code stealth. It was so uncomfortable it brought tears to my eyes. I carrier it for about 3 hours before listing it for sale.
I wanted a holster that is super minimal, rather than defeating the point of a .9” gun by adding 5/8” of hardware like the abovementioned. Among the inexpensive minimalist kydex holsters tulster seemed popular on sigtalk, after vedder. Kusiak came up again and again, as well

Stealth and incog are two different animals, but regardless if you expect comfort out of a cheap tulster then you’re going to be sadly disappointed. Sure a lot of people on forums buy them and recommend them, but many of them literally have nothing else to compare it to. There are a lot of first time gun buyer there that bought P365’s and they lack experience.

Tulsters are not comfortable nor quality holsters. I looked the kusiak up and I see it’s leather. Carrying a striker gun in a leather holster that flexes is a bad idea, people do it though. Vedders are also junk IMO and will wear hard on the slide finish too, been there, done that.

Maybe look at Tenicor, I have a few of their Glock holsters and they’re very nice and low profile. Or just a raven vanguard clip? I have one of those that I occasionally carry a non light P365 with when I want something smaller than my XL with the light and RDS and I forget I have it on me. Twice I’ve actually patted my groin to see if I had remembered my gun because I could not feel it even under the seat belt. I wouldn’t suggest it if you wear your pants at your hips AND go commando though, did that once when I was just tossing a pair of shorts on out of the shower and the front sight is not kind to the shaft to say the least.

What position are you carrying?

AIWB.
The vanguard clip means bare gun against my belly.
Kusiak is supposed to be rigid.

Well it seems like you already have your mind made up and those are the only two holsters that exist in your world for whatever reason. So why not just pick what you want instead of asking a group of strangers who obviously have their own personal preferences?

I wouldn’t use any of those holsters.

Minimalist holster suck for appendix carry.

I’d get one with a wedge/body contour as it’s much more comfortable.

Just my 2 cents.