That's a hard one to call. Henderson's main fault is no sewer and smaller. "BUT" it's in the middle of everything if your wife likes to shop like Miss Sue. Sites are crushed limestone and roomy with large bushes separating you from your neighbor. Very quiet except for traffic noise from US98. No cable but you can get Ft. Walton, Pensacola, Panama City and Dothan?? on your antenna and good satellite reception.
Topsail is more remote as you can't really walk to anything outside the park but there's a Wally World just down the road and good restaurants within 5mi. It has it all, paved sites, 50A, sewer and cable. Quite a walk to the beach on a private path which the tram also runs. If you have bikes they will be appreciated. Same beautiful beach just 5+ mi. difference. Much more traffic within the park unless you're on a site near the rear. *And it has a pool.
Both are great parks and hard to make a choice so take whichever one has an open space.
Enjoy
Dave