I think it's got to be my 2 female guppies. I love their personalities and the way they come up to talk to me. Though I have kept angelfish and bettas and kissing gouramis and khuulie loaches in the past (and a fair few others), I always did think female guppies were particularly gorgeous creatures. Alright, so I may be alone in this....
Also, my platy Smudge whom you all helped to cure from finrot.