My fave fish in my 29gal is my African Midas Blenny. Very friendly, and loves to 'say hi' to me whenever I go near the tank. He swims around all the time, and observes the family from his favorite perch when he is resting. Eats absolutely anything. What my clowns eat, he eats.
In my 29g I have
African Midas
2x Occelaris Clown
6-Line Wrasse
My 6-line has been a good citizen so far. A great cleaner of pods and common flatworms. Occasionally picks/cleans the other fish too. But, sometimes it can be a small nag to the other fish. It is fast, and thinks it owns the entire tank, even though it is the smallest fish.