1) Have Gun -- Will Travel: I don't remember this one being at all when I was a lad, but I discovered it as an adult and found it one of the best of the genre. Growing up, I really only knew it for the image of Richard Boone as the black-clad Paladin and of course "The Ballad of Paladin." It's an excellent program, though, and it's complete on DVD and streaming on Pluto (yet not, for no good reason that I know, on Paramount Plus).
2) Gunsmoke: I am required by law to mention Gunsmoke in any list of Western TV shows, and I am also required to mention William Conrad played the lead in the radio version. The half-hour version of the series lasted its first 6 seasons, and all episodes are on DVD and have aired in syndication. Unfortunately, these seasons are not on Paramount Plus nor Pluto at this time.
3) The Westerner: An excellent, thoughtful series from Sam Peckinpah (probably going places he wanted to on The Rifleman) and starring Brian Keith. At 13 episodes, it's an easy watch, and it's on DVD as well as various streamers, including free ones Tubi and Roku Channel as well as Prime Video.
4) Wanted: Dead or Alive: I haven't done a deep dive into this one, another series that I don't think was on much in my rerun-infested youth. It's highly marketable because of star Steve McQueen, so it is easy to find on DVD and is also on streamers like Starz and Prime. I do like what I have seen of it!
5) Bat Masterson: Another Prime Video star (but also found elsewhere and on DVD, though the best sets are harder to find and/or out of print). I always enjoy the characterization of cooler-than-thou Gene Barry as Bat, and the series' light touch is welcome but maybe has led to it being a bit underrated. It also boasts one of the best theme songs in TV history:
6) Dick Powell's Zane Gray Theater: An anthology with some great stories, it spawned The Rifleman and The Westerner! Powell produced, hosts, sometimes even stars. Unfortunately, DVD releases stalled out halfway through the series, but you can find many episodes on YouTube. This is one of my favorite show titles of all time, by the way.
7) A Man Called Shenandoah: I enjoyed the premise of this one: Robert Horton is a man left for dead and struggling to remember who he is. He roams the West trying to discover his identity. I watched the entire series on my dearly beloved but defunct Warner Archive Instant. It feels like a good candidate to pop up on Tubi someday, but for now you can get the Warner Archive DVD set.
8) Death Valley Days: Another anthology, with many episodes hosted by Ronald Reagan, and it is chock full of interesting stories and cool guests. I don't understand what happened to this one. Most episodes were issued on DVD, and for a while Starz streamed it. Yet now, despite the rightsholders (and maybe Starz, directly or indirectly) paying a lot to restore the episodes, it is MIA on streaming and you have to catch it on YouTube. Grit TV shows a few episodes every Saturday, but that seems like kind of a waste.
9) Tate: The title character in this 1960 summer replacement series is a Civil War vet who lost an arm in the conflict but continues as a bounty hunter. The uniqueness of the character adds a spin to the Western srories. Timeless (speaking of late and lamented; the company put out a lot of great DVD sets before Shout swallowed it and put an end to that) released the entire series, and you can find it on Tubi, Roku, and YouTube.
10) Yancy Derringer: Available on DVD and on Prime Video, this 1958 CBS series starred Jock Mahoney in the title role as a former Confederate officer working as a secret agent for the Feds in Reconstruction-era New Orleans. The setting and Derringer's dandy-ish image, plus the butt kicking of X Brands as his Native American sidekick, make this an interesting program.
There's 10 for you, and I didn't even include Lawman, Zorro, The Life and Legend of Wyatt Earp (with BOTNS icon Hugh O'Brian,Chuck Connors' Branded (Apparently butchered for syndication forever, I am sad to say), or The Rebel...nor many other half-hour oaters worth checking out!