Do you any of you use only WIFI as your main connection to your internet with your desktop?
What's your guys' experiences both positive & negative?
The newer mobos seem to have awesome WIFI.
I have never done so, but I may have to as the room that my new setup is going into is out of reach of my modem. 
I'd have to run a long ethernet cable from one room to the other, and that is something I don't want to do.

Wired is best

I have a wired connection to an extender, because my motherboard doesn't have wifi 

I used to only use Wifi, but I then had the chance to try out ethernet and that overall was much better, since its wired. My experience with Wifi wasn't bad, but there were obviously more internet-related issues compared to ethernet

Once I started using cable I never switched back. Wifi is best for phones and such.

Wifi in my apartment complex is super fast but occasionally it still bogs down. Usually not a huge interference to game play. But I do usually directly tether in

Never used WIFI, no matter what, ethernet is always faster and I never had a problem with the connections, I make sure both the PC and the PS5 can reach the modem.

I’ve used wifi in the past with no issues, but I’m hardwired now since the latency and speed is better.

Wired is the best way to go as I'm sure you can imagine. You just can't get the same performance without internet lag and sig drop. Stick with wired if you have the ability.

Have a Wifi 6 motherboard and router, literally no different for me than using ethernet.  Ended up moving my desk and going wifi only, because it's so fast.  Sometimes have trouble getting the 6 mhz band to connect but even at 5mhz, my wifi is faster than my internet speeds.

Momus123
can buying an ax card gets an improvement from ac router? 

I believe its lowest common denominator here. You may get new stability improvements or features relative to whatever has come out as a part of the new cards tech, but the band itself is going to be limited based on what AC can feed it. 

I used to be wired only but then I moved into a place that would require me to run a cable a great distance or use wireless. I have to say WiFi version 6 is pretty good and I have no problem recommending it for gaming as long as the whole system supports it you should be good. I know WiFi used to be horrible for gaming back in the B and even G days but now it’s really good and I can’t tell a difference really.

Wired all the way
wireless is bad on gaming

With decent hardware and good signal strength, wireless is perfectly fine.  wifi stability has come a long way in the last couple of years. 

Never use wifi for gaming