A rotary perspective
I can only help with rotary, but having worn both extensively the A20s ANC is much better at coping with the frequencies in both piston and turbine helicopters. Whilst the a30s are lighter, I think the build quality feels cheaper and sometimes have an awful buffet as the automatic adjustment of the ANC doesn’t cope well in a rotary cockpit. May be better in a quieter fixed wing cockpit.
Still I’d take a second hand set of a20s or Lightspeed over a A30 now with the prices of the Bose being equivalent of a small car! Unless you can find a good deal or get the tax knocked off through a business.