Having been a Kemepr user for 10 years now, I was the same at the start as OneEng1 in that I just wanted an all in one package and I hoped it sounded nearly as good as my valve amp.
I had a bumpy start because I used a guitar cab and carried on miccing it up and missed most of the benefit. My Cab was also pants even though I had Celestion speakers in it.
Once I broke away to FRFR and now to the Kabinet...oh my days! Never looked at another amp since and if mine was stolen, I'd buy another in a heartbeat.
Yes it has some flaws, rig manager can be a bit quirky sometimes and there was a time where everyone was talking about a mid range "honk" but I never had that problem. The test for me is I have NEVER had compliments on my sound prior to the KPA like I do now, often from users of other platforms.
Fractal, Helix and Quad ( and I assume Tonex now) are all really good, I'll never knock them but the Kemepr seems to have the easier path to great sounds and so is closer to a regular amp as a result. I'm not bothered about Dual amps and complex routing, Kemper have it right by focussing on the basics and nailing it.
About 3 months ago I bought a player....paired it with a Harley Benton GPA100 ( for £65!!) ran it into my Kabinet and.....exactly the same glorious sound. I have it as a backup just in case but I might bring it out for smaller gigs just so it gets some use!