Some people love one, and hate the other.
It’s generally agreed the A30 is inferior, or at most generous “no better” than the A20 - which was a gold standard.
I have the Delta Zulu, and I like it. Like most ANR systems it can “boom” especially if the ear seal isn’t perfect. I think because it does it a lot less, and quieter than my previous (The wireless Lightspeed) I don’t mind it. One of my colleagues hated it so much he returned the headset, and bought a Bose, and “feels sorry” for anyone with a Delta Zulu.
Another colleague and I swapped headsets for a flight. He preferred his A30, I preferred my Delta Zulu.
I guess that’s 2 votes for the Bose, one for the Delta Zulu. (If I needed another tomorrow - I’d buy the Lightspeed again. But my 2 colleagues wouldn’t!!)

Things I like:
Great rechargeable battery life.
Can carry a spare (included) battery pack with disposable battery’s loaded in case - I’ve done 8+ hrs a day and never needed it.
Can monitor battery charge on the app - not super accurate.
The custom EQ is good.
The connectivity is good.
The customer service is sensational - the previous wireless Tangos tested this. Unfortunately.
Not so much:
The charge cable is not USB - so basically have to buy a replacement from Lightspeed. (Something to do with connectivity features I don’t understand or use.)
You get no charge indication if you plug it in - no indication of if it’s even charging (always was) or when it’s fully charged. Turning it on, and checking the app works, but is extra effort.

AW189 & AW139 referenced above

Many thanks for this… food for thought!

Advice on headsets it not very useful unless you specify the aircraft you intend to use them in.

Anything will work in a PA-28. You don't need ANR in a PA-28. A Husky or Carbon Cub has a very much higher noise level. That shows up the weakness of ANR for receive and microphone noise cancellation for transmit.

If you can, try the headset you hope to buy in the aircraft you plan to use it in.

Thank you for this info… it is for a PA 28 Warrior…