My late wife and I bought a basic membership about nine years ago, while in our early 40s, and upgraded it five years ago. She was a sucker for a slick sales pitch.
We used Ocean Mist quite a bit, and I still do. Great park, and other than 4th of July or clamming weekends, I've never had a problem getting a beach loop site.
Ocean Breeze is like a **** car with a new Maaco paint job. It looks great 'til you get in. Stayed there before KM bought it, I hope they've fixed it up, but don't know. Diamond Point is nice, but seemed to have many full-timers who owned lots before KM bought the park. Its club house looked like the private craft room of a couple of the women there. Ponderosa is great, IMHO. Loved it a few years back. My "home park" is in Elma - drove through once, don't know why anyone would stay there. Haven't visited the others yet.
It's a mixed bag. For us, Ocean Mist sealed the deal. I can get there in a little under 2 hours. I've gone with the whole family, solo now that I'm widowed, and with a date. Good beach access, close enough to Ocean Shores or Seabrook for dinner, and I've always liked the hosts. I don't know if they still do pancake breakfasts or homemade cinnamon rolls. We really enjoyed that social aspect of the park.