I've always just done cellular. While I know one can do FaceTime Audio, it's just been slightly easier for me to call them normally. I only do this when I have AirPods.
I didn’t realize you could do FaceTime audio from the watch, but agree that the audio is like night and day when making a FaceTime voice call from my phone.
This question made me realize, I have never used the watch to make calls. However I have used it for incoming calls, it’s useful to see a call on my wrist and answer it (usually short convo) and not have to go look for where my phone is.
Usually use normal calls with AW. Will try FaceTime soon. Is there a way to answer an incoming call using Siri or setting a simple gesture without touching the watch? And to end a call? It can be useful in some situation.