For A Few Dollars More is so-so (but I’d still watch it again), but The Good, The Bad, And The Ugly is epic.
And if you enjoy them, then take a crack at High Plains Drifter or Pale Rider which are both excellent though share an underlying theme. The Outlaw Josey Wales is also well worth a watch, as is the magnificent (and best picture Oscar winner) Unforgiven starring and directed by an older, wiser, and grittier Clint Eastwood.
You might also want to add Yojimbo and The Seven Samurai to your list too - they’re the Kurasawa films that A Fistful of Dollars and The Magnificent Seven are western (in both senses) remakes of.