I've always heard recommendations from people that the Direct CU II cooler cools the best, but I never see numbers that actually support this. The ACX cooler tends to keep cards cooler, from what I've personally seen. It also seems that the ACX is more quiet.
I can't speak for the ASUS, but my EVGA GTX 780 ti hovers around 64-65C max load, while playing BF4, etc. I don't think I've ever seen it touch 70C (65% fan speed). I even have it overclocked to ~1240 core clock speed with a little bit of added voltage. I never hear the card fans either. I can't imagine the ASUS cooler being much better than this, but it's not impossible.