Breath of the Wild definately. Over 166 hours to complete the game (and not even 100%, not even close). It's truly open world game, you can literally go anywhere you can see (in the actual world area), which is something no other game has done. It's also challenging game, especially in the beginning (and not even counting the hero mode DLC which I haven't tried yet), and nice change from every other 3D Zelda. It was surprising to die against almost the first enemy in the game, unlike other 3D Zeldas where I haven't even seen the game over screen at all.
The graphics are beautiful, controls work perfectly, the weapon system is great and makes you use better strategies to save the durability. The quests were nice, especially shrine quests which were puzzles in itself, then the actual shrines also made good use of puzzles in typical Zelda style.
The music is really the only downside of the game, because there isn't much of it, but what is there is good. Overall one of the best games ever.