There's too many to pick from for me to pick only one. In general the malawian hapolochromis types are most enjoyable for me.
On an individual level, the first D. compressiceps I ever got was my most enjoyable fish. He was assertive, but not aggressive and, had stunning coloration and size. I had him for ~7+ years before he passed - he was probably 8-8.5 years old all told. Unfortunately every single D. compressiceps male I've gotten since has never been as nice as the first one was.