I'm really tempted to say Legend of Legacy, considering how fantastic its first-print edition is, and still worth just $40!
It has the potential to be another sleeper hit a la Etrian Odyssey IV (best-selling Etrian Odyssey including digital sales, but sadly rather underwhelming as a game)
Remember, Tomodachi Life was a massive sleeper hit - I believe it broke 4 million already, with at least a million outside Japan - and I don't see people here talking about it!
I WON A BET AGAINST AZUREN! WOOOOOOOOOOAAAAAAAAHHHHHHHHHHHHHHHHHHH
:3