I use rvparkreviews.com pretty extensively while planning my travels. I find the reviews pretty accurate most of the time. It's good to note the date of the last review(s) of a particular park. I've seen some outdated by 2 or 3 years. That being the case it's possible the RV park has changed substantially since the last review, making that review unreliable. Even so, rvparkreviews.com is a good general guide.
Another guide you might try is:
www.woodalls.comYou may find some RV parks rated here that aren't mentioned at the other website (and vice versa).