Silver Saddle is ok. I thought it was a well done late spaghetti but it lacked the nostalgia of other twilight spaghetti westerns, like Keoma.
On the other hand, Massacre Time is a genre classic. It is stylistically unusual with Fulci creating his own weird and surreal twist on Leone's style. It was a well thought out movie. I love the US dub (AIP, right?) on the WildEast DVD, which is far less intrusive than the UK dub on most releases.
Four of the Apocalypse is not quite as good, but still an excellent late spaghetti western. Unfortunately, it is hyped in the context of his zombie and slasher films, so its more lyrical and human elements are overlooked.