Well, it really depends on what type of experience you're after. HS doesn't allow smoking, drinking, fires, and is much more family friendly. It's a field where people can set up a tent, and expect a low key, quiet atmosphere. About 10 a minute walk to Town Park.
Ilium is set in a beautiful valley with a river flowing through it, and it's much more of a party atmosphere, without ever getting rowdy. It's the only campground where you can have a campfire, charcoal grills, and camp among the wilderness. It's about a 20 minute shuttle ride to Town Park, though you may wait for an hour or so to get on the shuttle during the late morning.
For me, Ilium is the obvious choice, as I enjoy camping in the woods, knocking back a few beers, and not worrying about families getting upset about picking circles going into the wee hours of the morning.
Listening to:
Panama Red - Old & In The Way