One of my favorite cameras was the FZ150. I loved that camera. It always did a nice job for me. But while suffering from a GAS attack one day, I bought a Sony A6000 with two kit lenses. It is an APS-C camera. Well, I got to say, jumping from 12MP to 24MP and being able to get decent photos with an ISO higher than ISO 800 was compelling. As good as my FZ150 was, there was definitely a step up in IQ with the A6000. But I did miss the 600mm zoom, and swapping lenses was turning out to be inconvenient. Besides, it seemed like every other lens swap needed a dust removal cleaning of the sensor.
So, I was slowly being drawn to the Sony RX10iii. 20MP, 24-600mm zoom. Arrrgh... GAS attack! I bit the bullet. Wow! it was twice the size and weight of the FZ150. But after a month, I no longer noticed a size or weight issue. It felt normal. Interestingly, the RX10iii's IQ was very comparable to the A6000. Granted it had the kit lenses which were OK, but not Sony's finest glass.
So, I had the same zoom range as the FZ150. A definite jump in IQ. No lens swapping, and a 4 times larger sensor, allowing much higher ISO values when the light got low. I was impressed. I since upgraded to the RX10iv with significantly better focus speed. It has the PDAF focusing and does a terrific job of tracking and eyeball detecting.
At the time, my only other choice was the FZ1000. It lacked the zoom range I craved, and according to the posts, it softened a bit at the long end. It was also very significantly cheaper than the RX10iii. But I threw caution to the wind and went for the top of the line. I have no regrets.
The A6000 was sold, and so was the beloved FZ150.
I looked long and hard at various APS-C cameras. Matching the 24-600mm zoom range would involve multiple lenses and those did not come cheap. Back to lens swapping again! There is not enough significant difference between the 20MP 1" sensor and the 24MP APS-C sensor with respect to resolution. You will have much narrower DOF with the APS-C sensor and the ability to use much higher ISO values. So, ask yourself, how much will you use the additional features in the higher end APS-C cameras? Will that be worth the 2x or 3x price to get to that level? For some folks it will. Again, personal preference.
Granted everybody's needs are different. I have reached the point where I get a high enough IQ to satisfy my personal needs. I am getting too old to haul around a bag of lenses and gear. Other than a couple spare batteries and SD cards, all my camera gear hangs from my neck strap.
I still peek at the specs of FF and APS-C cameras, but I have yet to see a feature that I am missing.