Impossible to really pick one, I'd go with Inquisition or Velnias though.
My main reason to be there was to see Velnias, Oakhelm, and Inquisition, and all 3 blew me away as expected.
It was great to see Wolven Ancestry and Woods of Ypres representing Canadian metal at HC3, I couldn't possibly think of 2 better bands from Ontario to represent us.
Ulveheim seemed to definitely impress everyone, I see bright things in the future for them now that they've made their presence known to North America.
Not too big on Folk-Metal but Metsatöll is an entirely different beast. These guys have such a powerful stage presence and energy that it's impossible not to like them, fucking amazing.