Square tiles...looks like they realized that the sphere system was flawed and absolutely paled in comparison to the perfection that is the square grid.
Ahem. The hexagon is my master...though I will admit, even squares are better than the movement field system Phantom Brave had. Amusingly enough, it didn't bother me in Arc the Lad: Twilight of the Spirits or in Temple of Elemental Evil.
Either way, if you really want a good movement grid, use hexagons. All hail the mighty hex!!!
(Yes, I grew up playing Battletech)