Much easier with a phenolic tip. More control with a leather tip. BUT way less jumpability with a leather tip. Also with practice you can have almost as much control with a phenolic tip.
You can however take a leather tip and cut it down to the last layer and treat it with some superglue and make a tip that has about 90% of the jumpability of a phenolic and still is easier to control than a phenolic.
I have done more jump shot exhibitions and lessons and experiments than I want to remember.