This pioneering Japanese RPG was first released in 2007 and paved the way for one of the greatest series in the history of level-grinders… The Etrian Odyssey series.
Number three is my favourite, but one and two are excellent too (see also the Nintendo 3DS fourth instalment), and all follow the same credo. Which is: to base a game around exploration, mapping, and turn-based combat. And to make the party system flexible, so that adventurers can take out different parties and experiment with character skills.