Zelda, even if it's cross-gen. I'd get both versions, but I'd play the NX version first probably, just like I played TP on Wii first and eventually played the GC version.
Other than that, a true 3D Mario game, or a true Paper Mario game (like the first 2). Basically, for me I need some major single-player experience at launch to make it worth it for me. Multiplayer-focused games (other than maybe Splatoon 2) won't be enough to justify a launch purchase, nor will lazy 2D platformers (I'm looking at you, NSMB series).
I regret buying the Wii U at launch and having nothing amazing to play for the first 10 months (I did enjoy Lego City a few months after launch), unlike Wii where I got Twilight Princess at launch. I waited for OoT3D for 3DS and was glad I did.
Upcoming Games To Get
Definite: Kirby Star Allies (Switch), Mario Tennis Aces (Switch), Fire Emblem (Switch), Yoshi (Switch), Pokemon (Switch), Kingdom Hearts 3 (PS4), Monster Hunter World (PS4)
Considering: Fe (Switch), Donkey Kong Country Tropical Freeze (Switch), The World Ends With You (Switch), Ys VIII (Switch), Street Fighter V: Arcade Edition (PS4), Kingdom Hearts 2.8 Remix (PS4), The Last Guardian (PS4), Shadow of the Colossus HD (PS4), Anthem (PS4), Shenmue 3 (PS4), WiLD (PS4)
