I haven't played Splatoon 1, so picking anything other than Calamari Inkantation is pretty much impossible. The only other one I know is Splattack.

For Splatoon 2, Low Tide. I don't know if that's a hot take, but I LOVE the mood of Low Tide.

For Octo Expansion, probably Regret. I think it's the basic bitch answer but I love that song.

Splatoon 3, nothing... Actually sticks out very much. Probably Anarchy Rainbow and souven1r for Side Order.