We usually stay at Mountain Shadows in Sandy (just South of downtown; right off the Interstate; and next to CW). FHU spaces are big enough, although you will get to know your neighbors. We have family in West Valley, so don't spend much time at the trailer.
We stayed at the Keep-On-Adding the first time we were in SLC and were not impressed. May if we had kids with us, but we don't.
I think MS is slightly cheaper than KOA and I find the staff friendlier. (Very nice laundry room, by the way.)
Reservations are almost required at either place. If you are not familiar with the Mormon Church's calendar, they frequently schedule assembly events for members from all over the Mountain West. Every RV space in the valley fills up without warning.
(A couple of years ago somebody said that Cherry Hill was out of business????)