15) Mallet Island Trio
This one I just don't like, it's the only boss I would consider outright bad. The problem is not Nightmare, which is a pushover but has interesting mechanics (healing the other pets and disappearing to heal himself), but Shadow & Griffon. They really hate telegraphing their attacks properly, it seems.
14) Throne Urizen
This one is not bad, but I don't know why they make you fight it 2/3 times, it's not an interesting fight at all. I've never enjoyed stationary bosses, and this one is not an exception. The battle itself is decent, though.
13) Qlipoth Roots
This one just... exists, I guess. For a first boss it's ok.
Another stationary boss, another decent fight which doesn't end up being actually fun to do. It's whatever.
11) Standing Urizen
More interesting than Urizen 1, but still not one of my favorite fights. There's not a lot to say about this one, it's more a tutorial for SDT than anything. Also, I need to find a way to avoid those tentacles.
As the first real boss, this one is average. It can be a bit awkward the first time, since you have limited mobility, but it's quite fun when you learn it.
Gimmick and spectacle boss, but not a bad one. It reminds me of a boss in Kingdom Hearts 2, I can't remember the name at the moment. Easy, but enjoyable.
This is actually a good boss. The gimmick here is always being close to the boss, and once you know a pair of tricks it becomes really easy, but there's quite a lot of fun to be had here.
7) Elder Geryon
Another good fight, I love the music on this one. Way better than its DMC 3 version.
This one is really well designed and also a bit weird until you don't understand it properly. Sometimes it goes berserk and can kill you very quickly, sometimes you can wail on it forever. However, when you get to know how it moves it becomes lots of fun.
5) King Cerberus
This one is better than his DMC 3 version, too. Several moves, and it can be quite hard, too. I like how you can approach this fight in many different ways.
4) Vergil vs Dante
Coming from a guy who doesn't enjoy Vergil 3 in DMC 3 (unpopular opinion, but I stand by it) this is way better designed, imo. Maybe I'd even say it's the hardest boss in the series. It has lots of moves and does crazy damage, so you have to be on your toes the whole time. I really like the arena as well, very reminiscent of DmC.
3) Final Urizen
I love this boss, it's so hype. Lots of moves, lots of possibilities and a beautiful setting which is also quite unusual for the series (the setting itself, not its beauty). Aside from the mechanics, which are great imo, I love the cutscene that starts after you beat it, with Nero and V talking about the rivalry between the two brothers while Dante finishes the enemy off. Such a fantastic climax.
2) Cavaliere Angelo
Credo Angelo 2.0, and it's amazing. Actually I might still like Credo a bit more, but this one is an outstanding boss as well. Not particularly hard, but it can fuck you up if you don't pay attention. Interesting attacks and different methods of approach, as well as the amazing OST, help elevate this fight to one of the absolute best in the series.
1) Vergil vs Nero
I love this fight (at least in Devil Hunter, then I'll explain why). It's easier than the one vs Dante, since Vergil's moveset is more lenient and he staggers more easily, but difficulty doesn't mean quality for me, and I still prefer it. Aside from the gameplay, what makes this fight so great are the dialogues and especially the music, I love Silver Bullet. Actually I have a nitpick with this boss, and it's that the vocals don't kick in if you don't do the second DT grab. On your first run you can't miss it, since you have infinite DT, but afterwards it's a possibility. However, the fact that I'm complaining about such a thing should show how much I love this battle.
And yep, this is all, let me know what you think. As a last complaint, I'll say that unfortunately I don't really like fighting Vergil on harder difficulties. I think that his fights are amazing in this game, but from SoS onwards it becomes a bit... frustrating and tedious, imo. He's not unfair, but he basically plays the whole fight by himself and doesn't let the player enough space. I hate that I always end up complaining about something in the Vergil fights (both in DMC 3 and 5), but that's how I feel. At least he doesn't heal as much as he did in his final DMC 3 form, which was kind of bullshit if you ask me.