Zelda and Fire Emblem are the two franchises I'll buy a system for, which is why I tend to buy Nintendo platforms shortly after launch.
The Tales of franchise used to be included in that small list, but I haven't felt as passionate about that series as I used to be. The SMT/Persona franchise has probably surpassed that as a system seller for me, though I'm not sure I can say it's reached that level yet.
Edit: I see this is more about specific games. I'm too lazy for that anyway....but I'll say BotW was my reason for buying a Switch at launch, despite it being multi-plat.
NNID: Zephyr25 / PSN: Zephyr--25 / Switch: SW-4450-3680-7334