Agreed. 'Stand' is the best album, but is basically made up of singles plus a long filler instrumental. All the ones up to Fresh are enjoyable, but this is a group where you can start with the 2CD Essential collection (amazing remastering) and really get the point of everything up through 'Stand' (plus a couple of classic single sides that aren't on any of the albums). 'Riot' needs to stand by itself. Each person needs to decide what they think of it, but it should be heard. 'Fresh' is good, but to me not absolutely essential. Nothing after that should be touched with a 10 foot pole, regardless of what the marketing on Rhino Handmade says.
I would agree completely except for one thing: Back On the Right Track, from 1979, has its moments. "Same Thing" is a personal favorite, for one. Sure, the album is not a Stone classic, so to speak, but any Sly fan should have it.