Which one do you like better and why?
This is just one opinion based on visiting both OSH booths twice and giving companies both the opportunity to explain why they're superior. The sound quality of both is excellent and reportedly the noise reduction of both is superior to ANR (I've been using Bose X and before that Lightspeed 3G). Both the Halo's and Clarity Aloft's are so light weight as to be barely noticeable. As I recall Halo said their set weighed less than an ounce.
If you need or want bluetooth or the ability to plug music into your headset, Clarity Aloft is your only choice.
The technology used is different between the headsets. CA puts a hearing aid speaker in your ear and uses a somewhat better foam (both companies agreed on this - I couldn't tell a difference, so it is probably minor). Halo has the speaker (and amplifier?) behind your head and has hollow tubes to port the sound to your ears. Both companies agreed that the Clarity Aloft mike is higher quality...CA thinks that's important and Halo said in the noisy airplane environment it doesn't matter....but the difference would show up if you're recording a symphony.
I could not tell any difference in sound quality between the two. My ears used to be really sensitive to sound quality...now I'd just say they're pretty good. The AOPA apparently ran an article that said they couldn't distinguish between them in terms of sound quality (here say from both booths). As I recall the Halo headset was $330 at the show and the CA's were $495 (bluetooth was more). $165 seemed like a lot of money for a music input jack.
I figured since I'll soon be able to plug music into my audio panel, I'd save the $165 and I ordered a set of the Halo's. The fact that my ears produce a lot of wax and the Halo's sell replacement ear tubes for $10 vs. sending the headset back to CA to clean or replace the speakers (not sure of the cost), was a small plus for Halo.
In a totally subjective realm, the gentlemen at the Clarity Aloft booth were knowledgeable about their product and I think fair about the differences but they were salesmen. Phil owns and runs Halo and ran the booth for the QT headset. He too is a salesman but he's also an audiologist and I felt like he gave better explanations about the engineering compromises made in the design of both sets.
Finally, while I was quizzing Phil on the Halo headset, Louise Hose brought a damaged Halo set back for repair. It looked to me like she and Paul had a tug of war going on and stretched the headset until bare wire was showing (since Paul says they have 5 sets, I'm guessing they were not fighting over who'd wear the set). As near as I could tell Phil was going to either fix or replace them at no cost. I don't know the details but he didn't seem the least bit phased about standing behind the product and that was a plus in my book.
My personal opinion is, if you like either one of these headsets, you'll like the other one, too. I can't imagine that you'd be unhappy with one and happy with they other - they're just too similar in performance. If you are comfortable with the "in the ear" headset then decide what features you need/want and get the set that suits you best.
This evaluation is based on visiting both booths twice during Oshkosh. My new Halo headset should arrive this week or next and I'm looking forward to trying them in a real cockpit environment.