I'm a dyed in the wool fish geek, so naming a favorite is kind of hard.
I will say that my favoriet group are the cichlids, and I've raised and bred many species over the years. Some rare and valuable, some just because I like them.
I used to HATE community fish. Tetras, that sort of thing. I called them "wimp" fish. Now that I'm getting older though ( a wopping 33 years) I find that I very much like those fish. At some point I want to do a planted tank with cardinals, gouramis, some clown loaches and maybe a few discus.
I very much like the large fish, and I've spent a lot of time keeping huge tanks full of giant central and south american fish. Red Tail cats, peacock bass, managuense, motoguense, shovelnose catfish, you name it.
Reef tanks are SO MUCH LESS MAINTENENCE! It's crazy. That's the main reason I don't keep huge freshwater fish tanks anymore. 50% water changes every week - Ughhh!
Jim