FWIW, I was looking at Bose, Sennheiser, and Lightspeed at Oshkosh. Here's my opinion, it's worth what you are paying for it.
Lightspeeds seem to break a lot.
You'll hear lots of good things about Lightspeed customer service and warranty / nonwarranty repairs. But that's because lots of people have had to use it. I have no idea what Bose or Dave Clark customer service is like. I've never had to use them.
The Lighspeeds seemed bulky and heavy for a premium ANR.
Sennheiser S1
Also big. The adaptive noise canceling sounded fantastic. The way it changes its canceling profile is very nice, and really made it quiet.
The headset was slightly bulkier than a Bose X, much larger than an A20.
The hinges felt flimsy, I had definite concerns about longevity, and with it being a new design, I was uncomfortable with paying top-self cash for an unproven design.
The control unit on the cable seems unnecessarily complex, and the buttons are small and could be difficult to adjust in flight. The volume is controlled by sliders with relatively short travel between all the way down and all the way up. It was hard to adjust volume without both ands and focusing on the unit, even when just standing in a vendor tent.
Bose A20
Comfortable. Smaller. Bose has been at this a very long time, and they have a great track record.
However, the smaller size also means that there is no noise reduction if power fails. They finally have LEMO connections with battery backup on the cable, and a LEMO adapter to use plug A20s with a LEMO and pass the power through.
The volume knobs are improved and protected against bumps changing volume, but they are easy to adjust without looking.
So, my list would be Bose or Lightspeed. But for me, the reliability is worth the money for Bose. Consider a used pair of Bose X. There are several on Amazon for $500 to 700. I would call Bose and ask how much for a refurbishment.
Sarasota Avionics has a set for $489 in Very Good condition and with a 3 month warranty.