I have owned an a6300 since about August of 2016. I also have an a6000. These are a few observations that I have, and that others in various Sony forum groups seem to share.
1) The a6300 probably has the sharpest 4K footage around. Maybe the D850 footage is sharper??? But for APS-C cameras, for pure resolution, I don't know if any other camera beats it.
2) The high-iso / low light performance is probably the biggest reason (along with the excellent resolution) to buy one over other cameras.
3) The 4k seems to me to have better moire handling than the GH5 or the D7500 / D500 in the sample I have seen, but I would try to verify that.
4) The 1080p is significantly worse than the 4K footage, but I don't know if it is really worse than most 1080p cameras. Some people say that it is worse than the 1080p footage of the a6000. Some other people say that the 1080p footage of the a6300 gets better if you DON'T use the XAVC S codec and instead use a codec with a lower bit rate.
5) The screen of the a6300 is highly reflective. It also dims when shooting 4K. They released firmware 2.0 to help reduce (not eliminate, but help reduce) overheating. Now with firmware 2.0 I think the screen gets EVEN DIMMER. It is very hard for me to see in bright conditions.
6) I have experienced overheating a couple of times. One time when it was about 85F outside (about 30C) and I was trying to shoot 4K video. I do tend to shoot short video clips (I am a real estate photographer / videographer) and my video shooting workflow is like this:
Set up tripod / slider -> pan back and forth / slide back and forth for 10 seconds -> review footage -> move tripod to new location -> repeat process.
So even though I only shoot for 10 seconds or so max before moving to a new spot and setting up again, my a6300 overheated in about 15 minutes time.
Worse than that, I then switched to my a6000 to shoot some 1080p outdoors and after about 15 minutes the a6000 overheated, too!!!
So I waited around and probably after about 20 minutes time I was able to use the a6300 again but I only used for about another 6 minutes before it overheated again.
This was BEFORE the new 2.0 firmware. So now it will probably do a bit better.
Another time the a6300 overheated on me when again it was about 85 degrees outside and this time when I was shooting STILLS. I shoot stills with the LCD 99% of the time (I almost never ever use the EVF).
7) Sony colors are kind of weird. You will most likely need to either purchase something like the Pro Color PDF or learn a lot about the different color spaces.
8) Sony a6300 controls are... different. Some people HATE them. Personally, I hated them when I first got the camera because I was use to photographing with Nikon D750 and D7000. Recently I broke my a6300 and I used my Nikon cameras again (for stills) and I soon discovered that it was hard to switch back to Nikon. The a6300 has a control dial on the back that does four or five different things (exposure compensation / ISO / drive mode / screen display settings / focus point selection are the defaults, I think), and although you might press the wrong part of the dial and end up adjusting ISO when you meant to adjust drive mode, it is so much easier (now) that to use the D750 where you have to use two hands (one to support the camera and another to both press down on a release lefer AND turn the drive mode button).
9) a6300 works excellent on a gimbal like the Zhiuyn Crane (although panasonic cameras do, too, as far as I know).
10) a6300 might have a bit better audio than Panasonic cameras??? No headphone jack, but people say the preamp on a6300 is better than preamp on GH5 / G85. But I would definitely research this.
11) For still photography - and for my type of work - my a6300 and Sony 10-18 is as good as my full-frame D750 and 18-35 AF-S G for all practical purposes.
I don't know if I can link to the videos on youtube, but Max Yuryev has a couple of videos comparing the GH5 to the a6500, and the g85 to the a6300 (I think) he uses both sony and panasonic cameras in his professional work.
Also, regarding low light / high iso , you might want to look at this thread regarding how some forum members view the lowlight capabilities of their GH5