I'm surprised people are saying Echoes, I read that people were disappointed for whatever reasons
Reviewers didn't like it because they started off with Awakening and Echoes is vastly different from the rest of the series, (and they didn't even finish the game, at least in Gamespot's case), others didn't like how the maps are simpler than Conquests as they're open fields. Then there are people who are apprehensive after hearing they dropped the weapon triangle. But Echoes entire battle system has been revamped, from Archers having 5 square distance range, mages using health to use spells, and only having one item to hold per unit. You can't compare it directly to the others as the different unique parts of the system have a lot synergy as a whole.
Aside from the battle system, the writing is leagues above Fates and Awakening. The characters feel like actual people as opposed to archetypes, the dialogue is much more mature, the VA is on point, and the OST is fantastic.
Wait... Whut??? Battle system has changed? Damn, gotta go read a review now. ---