I've played Hungary, Inca, some Maori, and Mali, and Mali is by far my favorite, with Hungary in second.
In my Mali game I started in a large desert that was protected by mountains, so I didn't have to worry about their early game disadvantages, and was able to fully utilize their abilities to make a very lucrative desert empire. Having Petra + Nazca lines + Solar panels made for some ridiculously good yields, and yield maximizing is one of my favorite parts about Civ VI. There's also the desert folklore + Suguba district combination which makes for some amazing district yields as well.
For Hungary it was really fun being able to control so many city-states, and have a powerful army without having to make the units myself. One thing I didn't like though was the fact I couldn't stop the Ottomans from killing my city-states since we were allies. There really should be an option to tell him to stop attacking my city-states, or else I'll have to declare war.