I'm currently flying a Topcap ARF. Had a Knife ARF. And I've flown a friends Magic on several occasions (and friend of mine has the Goldberg Ex-treme 330 as well).

IMHO, the Knife is the best of the lot. The Magic is the easiest to hover and the Ex-treme seems to be a stable flyer, but nothing can flat spin or knife loop quite like the Knife. Pull-pulls on both the rudder and elevator definitely give it a control edge. I'm still getting used to the Topcap, but it's rudder is way out there and doesn't seem to tumble like the Knife.