I'd say of the 3, Echoes needs a touch up the most. The game's color palette in particular left something to be desired. Brown and dead or...purple and dead. If the game ever does get a Remaster, I would like it if Light Ather showed some additional signs of recovery as you restore the planetary energy.

Also they need to do something about those mid-bosses. Probably the most brutal and unfair in the series.