Okay, so admittedly I love the spin-off title Dragon Warrior Monsters better than I do the main series. Nevertheless, Dragon Warrior Monsters still has a sizable place in my heart.
Dragon Warrior had its first title released on the NES as well, but Dragon Warrior III was the first in the series to have a party size of four characters. The game also featured multiple character classes such as soldier, fighter, wizard, and more which allowed you to customize your team to your liking - as well as improving the replayability factor. Dragon Warrior III is also one of the few games that can leave you terrified of a silver-colored smiling slime.
Dragon Warrior is no more, and has since been rebranded as Dragon Quest. It's the same game, sure. But nothing will ever replace the cringeworthy awesome title of Dragon Warrior in my mind.