I just finished watching Ultraman X (I love these affordable Mill Creek Blu-ray sets). It was pretty good, with some cool fights and decent characters. It was a lot more episodic then the first Ultraman I finished, Geed, and it had maybe a few too many bad filler episodes, along with two recap episodes, but overall I enjoyed it. It doesn't beat Geed by any stretch, I liked that shows characters better, and I liked that it had more of a plot. I'd probably put X a little below Ultraman Z (based on how Z has been so far), but still definitely worth watching if you like Ultraman.
Next up, I'm watching the Ultraman x movie, which was apparently released on the 50th anniversary of the original Ultraman series, and it has the original Ultraman appear. After that, I'll probably go to Orb since I have that Blu-ray set.