AusBonsai

I have done airlayering successfully in the pass with sphagnum moss.
Now, I wonder one can use soil, well drainage ones?
Which is better? Moss or soil?

I have experimented with diatomite, zeolite and vermiculite with a little bit of sphagnum mixed in. I tried this after getting tired of having to comb out sphagnum moss for the next few years from the rootball. I have gone back to sphagnum as the other mix doesn't stay moist enough. It works OK with figs but doesn't work very well with other species.

I don't think one is better than the other. It just depends what you are used to and what conditions you have.
Personally I use sphagnum. I think there is more than just water capacity in sphagnum because I have struck cuttings that otherwise would not have grown. possibly some hormones or growth promotants in the moss that other mixes don't have? note that sphagnum was used to treat wounds at one stage because it helped prevent infection???
A nearby Ausbonsai member swears that pots with his normal potting mix are far better for layers at his place.

If you can keep them watered, pots with good potting mix are probably equal, maybe better than sphagnum in plastic. On garden plants where watering is irregular, plastic wrapped sphagnum is probably superior.

Do some trials and let us know what works better for you.