Any of the onsites are great, and each have unique qualities.
HRH - Closest to the parks, 5 minute walk.
RPR - Lowest priced, 7 minute walk, huge pool.
PBH - 13 minute walk, biggest rooms, beautiful resort.
If you go super early like you're thinking, there is an advantage, even if you are staying onsite. That would be getting into the park before everyone else, because there is no rope drop. The gates open, and that's when people are let in. The advantage is getting front seat rides on Hulk and Dueling Dragons with no wait. I'd say the boats start running around 8am and there won't be a line that early. If they haven't started then walk.
Going back has no wait for the boats if you leave before the park closes. If it rains, the boats will stop running and everyone crowds the shuttle van. If that happens you'll have to walk.