If I had to have just one of those planes, I'd go for the Goldberg.

Knife is marginally easier to KE (less coupling) and Hover (less torquing). The Goldberg snaps better and is a couple of ounces lighter. I have both planes and ususally take the Goldberg unless I'm practicing tail touches.

For a nice tight KE spin or waterfall, mix down aileron with down elevator and up with up, don't use a Y harness.