Both are great parks. For swimming I think Huntington Beach is the best in the state. Everything located within a single entrance to the park. Close to good restaurants and close enough to MB for the attractions.
Hunting Island is much more isolated. About 80 sites are now in the ocean. When you first arrive to campground and see all the tress missing it is a little disturbing. Once you get in deeper it is fine. Park is divided into 2 entrances, though you can hike/bike back and forth. Camping is one entrance everything else down further. This past year the non camping side closed a couple times due to flooding.
If kids are involved, Huntington Beach is better. For quiet camping we now do Edisto Island at the Oak campground.
Ridgeway, SC
2019 26DBH Grey Wolf