Kind of a general topic, but personally I really only have experience in Switch games so..
A bunch of Switch titles have a Ranked online option and I'm really enjoying playing each of em.
Splatoon 2 (currently hovering around C rank, second from the bottom)
Pokken Tournament DX (I think like E3.. very low, and only a 29% win ratio, would be easier if I changed to another main my DAMN I love Scizor)
ARMS (rank 5 out of a max 15)
It can be heart-breaking losing rank, particularity since the WiFi is quite weak on my Switch and on the odd occasion I get a communication error and get d/c'd + lose rank.
Note: I am by no means highly ranked in any of these games, maybe if I were to persevere with just one I'd climb the ranks a little higher, but I just find the added competitive aspect just that little bit more rewarding.
MK8DX also has a ranked mode but I've barely touched the game.
Anyone else frequent this mode in your chosen game(s)?