Me I'm not a music enthusiast o, but with what I have seen outside Nigeria (when I discuss Nigeria with a random person outside Nigeria - which I have done in at least 20 countries), here is the order of popularity in recent years:
1. Burna Boy
2. Davido
3. Wizkid
Rema, Yemi Alade and some other random guys I don't even know are also a shout for that 3rd spot. Or 4th below.
Talking about random guys, I didn't even know Ric Hassani was Nigerian until a Tanzanian mentioned him as his favourite Nigerian artiste.
But Burna Boy is the most consistent first mention.