Been watching westerns since I was a kid, definitely my favourite movie genre.
My top 10 recommendations would be
Once upon a time in the west (best film of all time IMO)
For a few dollars more
Butch Cassidy and the Sundance Kid
The Good the Bad and The Ugly
The Outlaw Josey Wales
True Grit (John Wayne version)
For some older ones I would also recomment the Gunslinger (gregory peck) High Noon (gary cooper)and Hombre (paul newman)as well as anything with John Wayne in. Enjoyed Pale Rider and the Wild Bunch as well.
Newer westerns - the New 3.10 to Yuma was pretty good,