Rikkitic:

 

I don't think there is one single measure of species success. The ability of cats to appeal to humans and take full advantage of that counts for a lot. Also the fact that cats will do perfectly well when we are no longer on the scene to wait on them. They are clever and resourceful. And they are not banned as pets. They win in my book.  

 

In evolutionary terms, I reckon success means that the organism hasn't changed for a very long time. Meaning that they have found a body type that works well enough to survive over millions of years. By that metric, I'd suggest the cockroach, or maybe the nautilus. They just keep on surviving and reproducing, which ultimately is the only real indicator of success as a species.

I still vote for the cats. I should have entitled this 'species I most want to succeed'.