Tonearm mounting differences Graham vs.Tri-Planar.

One of the best? At its price point I'd say yes.

Syntax has compared Tri-P vs. Graham Phantom using a UNIverse. I believe he prefers the Phantom with that cartridge. That's a bit costlier though, as you have to buy a tonearm cable.

Schroeder arms are also good with Airy 3. Softer bass than a Tri-P but quiet and with a low sound floor, which helps the Airy 3. It's a lively cartridge and likes a quiet arm.

The Durand Talea is the best tonearm I've personally heard (with ZYX UNIverse or Ortofon A-90). I've no doubt it would be exceptional with an Airy 3 also, it's the quietest tonearm I've never heard but sacrifices nothing in terms of solidity. Quite a bit costlier than Tri-P however.

Dougdeacon, thanks for sharing your experience.
The Talea and Syntax a bit too pricy.
What other tonearm options for Airy 3 would you recomend, in a range of $2k-$3k?

Quite a bit costlier than Tri-P however.

The Triplanar has considerably harder bearings (hardest made anywhere in the world) and are thus the most durable; also having the least friction. However its not a $2K-$3K contender unless you find one used.

My findings are different from Doug's; IMO (using recordings I have recorded and released on LP as reference), the Triplanar is the more neutral arm for less money.