You have Fractal equipment, you were biased to dislike the Katana, of course, a cheap $300 amp is not going to sound anywhere near as good as a $3000 modeler. For people who have never tried Axe FX, Helix, Neural DSP, Kemper, etc the Katana probably sounds awesome to them.
Powered monitors bound you to a desk and look nothing like a guitar rig setup and FRFR speakers, based on reviews I read on forums, Amazon, etc people complain that they are very loud even at the lowest volume setting.
The point is Fractal is not for everyone and not everyone has or wants to spend that much money to play in their room. The FM3 is "affordable" but then you need to buy good powered monitors, it adds up to the total. What I don't like about this studio monitor setup is that it bounds you to a desk, is not very portable or nice looking, it just doesn't look like a guitar rig.
The only reason I was considering the Katana is because for one I tried it in person, where can you try an Axe Fx? and it has the 0.5w setting, so I assumed it would be good for low volumes bedroom playing.
If I were to get an Axe FX, I'd rather have a more guitar-like setup, such as a cabinet with the rack on top of it. That's the look I like and I would go for. The idea of having an FM3 on my desk with monitors around it, pretty bound to a desk, I guess is the modern thing to do these days, but I don't find it too appealing that's all. I prefer the old school look of amps