I vote for Hayden-Harnett. They have superior quality. The leather, the stitching, the lining, the hardware, everything is nice. You can tell when you get one in hand.
I like Tano too. But it's a matter of personal style - what I notice is that Tano bags have a more casual style than HH. They do not have cotton or twill linings in the bags, but nylon. The stitching is not as neat either. However, if I wear my Abercrombie&Fitch or American Eagle Outfitter clothes a Tano bag will be more suitable than a Hayden-Harnett bag IMO. So I guess it's really up to your need.