For me personally it would have to be Mario Kart 8. I can play that game for hours (which I do) and it'll never get old! I like Splatoon, I still play it sometimes on the Wii U, but it aggravates me to no end. I would say buy Mario Kart 8 and then save your pennies for Splatoon later on. Nintendo has already said Splatfests for 2 years!