Depends on the kind of scenery you like to see. I love both, but hiking is a little harder (at least with a full pack to lug), and need more concentrated scenery. I prefer to get out there on longish days on a bike, and see more of what there is to see. But then the traffic can get to be an annoyance.
Hiking is better for wildlife viewing, but biking is better for meeting people and having a nice chat at a wayside stop. I think for me hiking is much more solitary, biking more social. How alone do you want to feel.