I'll just come right out and say it - Westerns aren't my favorite movie genre, and I don't have much experience with them. But there are a few that stick in my mind.
Blazing Saddles - We own this one. It is goofy as all get out, and laugh-out-loud funny when you are in the right mood. There are at least a half dozen lines that come out of my husband's mouth on a regular basis around here (I'll leave it up to you to figure those out!).
Unforgiven - There aren't too many westerns that can claim a Best Picture Oscar, and keep my attention for 2 hours. This one did. It didn't hurt that it was packed full of talent, like Eastwood, Gene Hackman and Morgan Freeman.
Shane - There is a Roger Waters song from Pros and Cons of Hitchhiking that features a child screaming "Shane! My mother wants you!". I was always intrigued by this, and finally watched the movie to see what it was all about. What I found was an incredible movie. A dashing man comes riding into town to protect it from evildoers. And yes, that child's mother DOES want Shane, in a big way!
Hang 'Em High - I can't even legitimately tell you this is Clint Eastwood's best western, because it is the only one I've seen. It still is full of action and plot development. Most importantly, back then Clint was THE DUDE.