Best Final Chapter in the series

[Lau]

I really liked Grima. The map aesthetics were gorgeous, and the music was just A++. Yes, it can be two-turned, I've done it myself, but there's nothing better than sending Robin to slaughter Grima. It just fits into the story so well, and...I love it.

[Rex Glacies]

Judging from what I've played:

Spoiler

Grima - Cool and epic. I actually liked how you fought the Grimleal rather than Risen, as it showed that Grima still has human followers willing to die for him (and is a foil for The Future Past DLC, where everyone has literally died). However, Grima could have just done a barrel roll and be done with us, which puts a damper on the epicness.

Light - The one I chose as my favorite. It was neat fighting morphs of past adversaries one by one as the doors opened, and they all provided a decent challenge. The Fire Dragon was a bit out-of-the-blue, as was Ninian's resurrection, but it was altogether a really good chapter, both in gameplay and story.

Night Breaks Through - Also out-of-the-blue, but it did place a cool conclusion to the Takumi arc.

Dawn Breaks Through - Again, out-of-the-blue. But unlike the Fire Dragon or Takumi, which expanded the plot a bit more or provided a new enemy to fight, this was just Garon 2.0 without doing anything to change the story or gameplay, as he really isn't much stronger than his human form.

Anankos - Even worse with Anankos's random power surge via devouring Garon. But it was one heck of a multi phased fight, so I'll give it that. Frankly, judging by pure gameplay experience, I'd say this was one of the best in the series due to how much health and damage this thing had.

Together to the End - Another really good one. Giving names to the various Duma Faithful was unnecessary but added a bit of immersion as it presented them as not faceless nobodies but members of a cult that had as much a reason to fight as you do.

[Interdimensional Observer]

I just replayed the final battles of Revelation. It wasn't so bad as I remembered. Partly because this was the end of my nearly back to back first set of Conquest-Birthright-Rev runs. I just wanted to get it over with and rushed more than I should have.

The first time I did C27, I did a one turn clear. On Lunatic (my first run was Hard) I decided against crunching the logistics and strategy of a one turn and instead spent ~8 (maybe 10 at most) turns on the fight. I thought there would be obnoxious reinforcements, not a single one on that map thank goodness. Since resource use doesn't save after beating the game, I used a bunch of stat boosters and many tonics, mostly on Corrin. Corrin safely dragontanked most enemies with a Gunter battery and a Concoction and Vulnerary, Draconic Hexing them in return. Paired and Speed + Defense Rallied Xander and Ryoma held a chokepoint and they helped whittle down the enemy numbers. The enemy's fliers went their own ways and were dispatched easily. When the enemy numbers had declined enough, I finished off the mass and then killed the Sorcerers who were the last thing between me and Anankos. 

C28 was much easier than last time. Not rushing, knowing there were two head phases and reinforcement that would be coming from the sides, I moved with a little caution because I'd hate to have to replay the prior battle, and spread out my forces over the whole area and baited or killed all I safely could. I managed to kill off all starting enemies by the second turn and had the reinforcements, a mere 2 per turn, under control. Paired Xander and a solo Ryoma killed the right hand without any fuss, with Corrin with Gunter took out the left. Corrin then moved back to the center and dispatched both the head and heart with relative ease. Sakura had a Physic and while I had another I should have given to Shura, with Dual Guards and one or two dodges, I didn't take that much damage and could slay Anankos fairly easily.

RD 4-Final-5 is actually rather close to Endgame Rev- since neither the Silent Dragon nor Order Incarnate is that much of a threat. The Auras are harmless with Nihil, and Anankos's parts don't move (nor get healed like Ashera and her Auras) so you can fight them only when ready, and both need multiple attackers to take out barring the most optimal of setups. The Spirit reinforcements are weak, while Anankos's are stronger and he has more starting allies, but once you get them taken care of, it is easy to neuter both the Spirits and the Vallites. Anankos is stronger statistically, but he has no real tricks beyond a strong hit, and stat buffs are much more plentiful in Fates than RD (they didn't even give him Garon's Draconic Hex), so it evens out. Ashera has her strong single target and weaker AoE- but both are bearable, particularly the latter if you brought the Fortify, which Micaiah can always use since she gets auto S Staff on promotion to Light Priestess. The maps are smallish and quite open.

So in short, my opinion on Rev's final battle has changed. FE has generally weak final battles in one way or another, but Rev's, in spite of many earlier objectionable maps in the route, isn't so bad after all. I think BR's is worse now actually since it has a harder and longer, but not for good reasons 27, and the Endgame is just a quick bosskill. And of course Awakening's (including Future Past's) final fight is worse. Not to say Rev has a masterpiece, it doesn't, but it isn't an atrocity either.