I love both but favor running.
It's a lot harder.
Better for the knees
My coach always want me to use bicycle, he said that running harms knee joints more than biking.
You go faster, it burns calories faster, and cyclists are generally more fit than runners. Not to mention that it's incredibly fun.
Biking. Cause It's more fun, plus you can travel more distance using more muscles in less time!
It helps you burn calories faster than running!