Of the four, I would have to give the lifetime achievement award to Neil Young--I think his Freedom album, his solo effort following a CSNY reunion/new studio album (around 89), is one of the finest rock and roll records ever made--it became my favorite "new" rock and roll record at the time--at least until Phobia came out 2 years later.
Steven Stills is a fine guitarist. Three songs, in three different bands, were sensational, IMHO. First, For What It's Worth--a great hit single--with Buffalo Springfield. Second, Suite Judy Blue Eyes--despite all the air play, still sounds great, just a wonderful love song with magical harmonies. Third, his hidden gem for the ages--Johnnies Garden from the Manassas album.
But I can count dozens of Neil Young songs that were sensational--Few other than Ray Davies can point to a more impressive catalog of originals over the decades.
Other ghosts from the past--Art Punk, TedStar, TedMor, Zeno, Dr. T--the name is Ted