I usually lurk, but this is something I feel like I actually know about, so I’ll weigh in here.
I have experience with Lightspeed, David Clark, Bose A20, and Bose QC 35 using the NFlight Nomad mic, along with a litany of passive headsets. Moreover, I fly in a wide range of GA planes, including an RV-7, a Great Lakes biplane, Yak-52, Cirrus, and Citation Mustang, as well as towing gliders.
The best of these headsets is definitely the Bose A20. It’s very good. The ANR is excellent, and I’ve made phone calls from the plane over Bluetooth where the recipient didn’t know I was in an airplane. The price tag is eye-watering, though, and they aren't exactly robust. My peer group and I have spent a lot of money sending headsets back for refurbishment, which is also way more expensive than it should be. I don’t find them suitable for the more hard core environments like the biplane or the Yak-52.
In my opinion, the Lightspeed headsets are fine, but nothing to write home about. The ANR is adequate, but not great, and I’ve found them to be rather flimsy. David Clark are great passive headsets, but my experience with their ANR has been pathetic. I love my DC ANR headset, and I have it in a helmet and use it in the Yak and the Biplane, and it works well in those challenging environments, but it's essentially passive.
My favorite of all of these is my NFlight Nomad mic, paired with a set of Bose QC 35s. Bose will tell you that the consumer-grade hardware in the QC-series isn't as robust as that in the A20, which is kinda true. But, The fact that it's consumer-grade hardware cuts both ways. On the one hand, the units aren't as robust as the A20. On the other, they last for a really long time on a single charge, can be charged at any USB port, and aren't particularly expensive to replace when they crap out. Plus, they're light. I must have an unusually sensitive head top or something, because after about 2 hours of wearing the A20s, my head starts to bother me seriously. The QC 35s are much less intrusive in that way. I wear these things all day sometimes. That's a particularly nice feature for muggles, since they care more about creature comforts than we grizzled veterans do.
One drawback is that the QC-35s only last me about two years, and then they start to go belly up. I'm on my second set of QC 35s now, and the first one gave out completely in the left cup, and the second one is starting to crackle on takeoff. I'm probably harder on them than most people are. I have a buddy who taxied over his, and they still work fine. Another drawback is that they have internal batteries, so need to be charged periodically. You can't just leave them in your plane and keep a bunch of spare batteries around. This isn't a problem for me, because I use them daily for music and the phone, but it might be an issue for people who don't do that. I hear the Sony headphones work well with the mics, too, but I haven't tried them.
For passenger use, the QC 35 is a great choice. You can add in an NFlight mic if they want to be plugged into the intercom and listen to ATC, or they can use it with their phone or tablet or whatever.
My $0.02,
Shaun
. Will do!