If you liked the Catman Series II anime, the Anime-Planet community thinks you'd like:
Every town needs a hero. Unfortunately for the human residents of Dark City, theirs is a stray cat. Swooping from roof to roof, its first thought is always of food or being able to catch an elusive mouse – saving the day is just a fortunate side effect. From rescuing lost children to putting a stop to careless littering, Dark Cat finds himself caught up in numerous problems – though caring about none of them. As his name spreads, he finds himself the center of attention as reporters desperately try to snap the unlikely hero. Cheeky and mischievous, this feline favorite wants to protect his kind; but can this renegade kitty stay out of the clutches of a mayor determined to rid the city of strays?
Both series take a look at cats in the human world that cause interesting situations. Dark Cat actually has humans in the show where Catman turn cats into human like beings living out their daily lives. Both have a interesting soundtrack that helps the viewer feel more about the show, especially in Catman. Both are abstracty in their style and have short episode lengths, if you liked one I'm sure you'd enjoy the other.
If you enjoyed seeing the humorous situations that Catman found himself in, then it's worth checking out the mischievous Ankoku Cat. While Catman is generally more coarse, if you enjoyed the comedic aspect of it, then you will likely enjoy Ankoku Cat.
Dark Side Cat and Catman II are both short anime about a cat who doesn't really fit in, who tries his hardest to be the best at what he does, but usually fails. The animation styles are also what these titles share, so consider watching both.
His name is Tortov Roddle, and he is a traveler from Tortalia. Along with his unusually large companion of a pig, the slender Tortov travels from place to place, always finding a new and beautiful adventure at his destination. From islands carried on the backs of frogs, to delightful cafes, to movie theaters and giant bears, there's a wonderful story to tell in the diary of Tortov Roddle.
A adventure-seeking, lonely traveller is the main character of both Tortov Roddle and Catman II. Though the latter is a little more action-packed and foul-languaged, there's something similair in the animation style of these titles that set them apart from the mass. I see no reason to skip one or the other.