Man are you ready to open this can-o-worms, you'll get comments that say the Nat'l parks in their region is the best??
Here goes, I've been to Nat'l parks from OKEFENOKEE Swamp. to Mt. Baker/Mt.St.Helens and never been to the ones in the NE. It all depends on the time of year and temps you want to put up with! I personally think the most picturesque are the parks in the North West.
One summer we visited White Sands Nat'l Park ,NM, Painted Desert, Grand Canyon, Yellowstone, Grand Tetons, Great Redwoods,Mt. St. Helens, Mt Ranier. Mt. Baker. This was accomplished within 30 days (Mil.Leave ).
This is where YOUR choices take over , What do YOU want to see? How long do you want to stay?
Since you are in SC and you mentioned HIKING, Have you considered Hiking the Blue Ridge? Beautiful in the FALL and comfortable temps to camp in.
Xnavylfr(CHUCK)