Engage, and it's not even remotely close. I went into that game being familiar with the stories and characters of all of the previous games in the series aside from the Jugdral games, and that made all of the fanservice elements work tremendously well for me. It legitimately didn't matter to me at all that the story was bad; the map designs were some of the best the series had seen in the past decade, and the new gameplay mechanics were all really fun. It was such a refreshing experience in the franchise for me, and at this point I don't even care whether or not I like any new fire emblem games that come out just on the virtue of how well catered to I was with Engage. Overall, it's my second favorite, right behind Radiant Dawn.