As others have said numerous times, I enjoy the individuality that Nintendo is allowing Splatoon to have, to develop its own identity. Right now I'd prefer more Splatoon cameos in other games rather than other games' cameos in Splatoon.
Interesting that this thread back in November had proposed Nintendo themed Splatfest polls and we just got the Pokemon one, which was IMO the most exciting. I know that it was celebrating Pokemon's anniversary, and few other series have enough widespread recognition (and game-based allegiances) to warrant a Splatfest poll, but I definitely would enjoy more Splatfests like that. Mario or Luigi. Old School or New School (like NES-N64 vs GCN-WIIU, maybe). IDK