Zelda is the big one for me. And now that Xenoblade seems to be a franchise, that would be up there with Zelda. And if Fire Emblem continues on the path of Awakening/Fates, then that would be in the "big 3" with Zelda and Xeno for me.
Aside from that, 3D Mario is a strong influencer. A TRUE successor to 64 would be an instant system seller. The Sunshine/Galaxy/World/Land series are influential and can tip the scales, but I wouldn't buy a system just for them. Having Mario Kart and Smash Bros. out or coming soon helps.
Specifically for handhelds, the main Pokemon RPG series is a pretty strong factor.
For non-Nintendo systems, Kingdom Hearts is probably the game that'll get me to buy a PS4. Street Fighter, Final Fantasy XV and all the other 3rd-party options and variety helps, too.
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)
