Having skied Colorado, Utah, France, Switzerland, Italy, Autria, Germany, NZ and Argentina, I would say Bariloche, Argentina indeed has the best trees I have ever skied... so far.
What you want is wide spaced trees with no branches at the bottom and lots of stuff to play with (fallen trees, cliffs, pillows). That describes Bariloche, pretty much.
Some lesser-known resorts in Switzerland also have epic tree skiing that looks a lot like those BC videos posted above. Some of the best tree-days of my life have been in Spluegen and in San Bernardino, both in Switzerland.
Colorado has been disappointing so far (Copper, Breck, Keystone, A-basin, Vail, Aspen). Trees are too tight together and shit gets scraped because there are so many people skiing these resorts.
I still have to ski BC and Japan though, I expect both to be incredible for tree skiing!