Josey Wales and High Plains Drifter (where's the Blu-Ray!?) have always been my favorite Eastwoods...
But I prefer High Plains Drifter. Just cant beat the haunting, brooding mood. And the moment the whip lands on the saloon floor is cinematic gold...
Unforgiven is third on my list from Clint, then the Spaghetti Trilogy. And yes - I suffered through Paint Your Wagon!
Other than Eastwood...
From the 80's was Silverado. Light and clean, tip of the hat to the classics. Hard to beat. Brought the genre back into the light.
In the 90's, other than Clint's oscar-winner, for me it is Tombstone. Hollywood western, not doubt, not terribly gritty, in fact, a bit glitzy. But fun all around and well crafted.
2000's would be a toss up between True Grit and 3:10 To Yuma. Both finely crafted films, deftly handled, and films that told a great story masterfully well, using the genre as a setting, rather than as a crutch.
But to recapitulate...
If I could have only one western in my collection, it would be High Plains Drifter.