Well, the A&H ACS 3-piece and the Qarbon Nano QN2 are very similar on paper and physical characteristics... Shooting characteristics are a bit different, but that is more due to material differences of bamboo or actionboo on the A&H and foam on the Qarbon Nano... I'm not going to say one is better then the other as truthfully I like both... their just different...
Both bows would be what I'd call top tier bows and both companies have very good track records and Customer Service for both is top notch! It would come down to personal perference, and right now (since I currently have one...) I'd pick the Qarbon Nano QN2... :D