Which models are you referring to? I doubt there's been many who have heard both. I've only been able to demo the M60s and M22s. I've owned several HTD models (the old ones), plus their new L3 center (with the ribbon). I've been using it for about 2 weeks now in place of my Rocket RSC200.
Your best bet is to listen to both and determine which you may like better.
If possible, you can order a pair of Axiom and bring them over to HTD headquarters to do a comparison.