Just my opinion, so take it for what it's worth, and based on sample size of just my experiences.
My ratings of what I have/had:
1. Freedom Ordnance FX9 - accurate, superb ergonomics, the easiest and fastest field strip down to firing pin (under 15 seconds) of all the ones I have owned. Fun to shoot. Had to send it back to Wolverine to correct an issue with last round bolt hold open and bolt release, but upon receiving back it is smooth like butter. Downsides is that it gets really dirty really fast, and seems to be picky on ammo. FO doesn't recommend shooting aluminum cased ammo out of it. Also, they do recommend a break in period using just 115gr FMJ from certain brands though they never called it a break in period, when I talked with them about it.
2. Ruger PC Carbine - mine is the aluminum handguard version with six position stock. Pluses include ability to take apart easily into two pieces for backpacking. Good gun, reliable, but several things I don't like about it: a) take down requires tools and is involved and takes a lot of time compared to my FX9 b) some components are frail and with take down can wear/break - shock buffer and c clip - replace right away c) gun is barrel heavy on the aluminum HG version, d) the recommended Ruger torque strength of 65 inch pounds (yes, it's in the manual) on the two main screws WILL strip them... That said, it is a Ruger so very reliable and accurate, though not as accurate as my FX9
3. Kriss Vector - interesting design, but novelty wore off fast. Vectoring system is useless on a 9mm, so it's gimmicky they market it on a 9mm. Cannot shoot +p loads. Chunky barrel, heavy. Don't like the charging handle style/function, a bit overpriced for what you are getting. I have since sold mine.
4. Keltec Sub2000. Bought it initially for the folding feature. Found out that novelty wears off. Mine was in .40SW. Several things I didn't like a) onboard sights are TERRIBLE. I can think of worst words to use but that is beyond my personal ethic to use them. b) charging handle design and location I never liked. The CH was extremely heavy to operate even years later. Can't put an optic on it when folding unless you buy a $260 offset mount. And an optic is needed since...well, see point A. The whole thing felt cheap. That said, it always went bang, though because of the light weight and being .40, you really felt the recoil. I did like the fact that the mag was in the grip, though. I have since sold the thing.
EDIT: Oh, I also had a TNW ASR in 9mm, which I sold a couple of years ago. That was OK, can be taken apart in two pieces for backpacking with a simple unscrewing of the barrel. Was OK, no wow factor, but ran fine. Not a fan of the hold the bolt open via a notch - mine slipped occasionally. The support from TNW though, was nonexistent. It took different mags without issue. I sold as I got other PCCs.