Beat Darksiders. The only major downside to the final boss fight was that he really didn't do that much damage (to be fair Abyssal Armor kinda does that).
In order of preference I'd probably order the bosses (and minibosses) as such:
Difficulty, fun in fighting them, ingenuity to the strategy, etc. are the factors I'm mainly basing this on. The Griever was really good right until you could actually damage it, which is when it went down in 10 seconds. The Stygian was decent, but it had a lot of wasted potential. Silitha was cool in concept, but the completely random difficulty was a bit of a deal-killer. Straga may have been pitifully easy, but the concept for how to fight the fight was interesting. Uriel wasn't hard, but her attacks were varied and could undoubtedly pose a legitimate threat. Tiamat may have been brutally difficult, but everything about the fight was absolutely epic. The Guardians in Black Throne were rather easy, but, like Straga, an interesting sort to fight against. Arena Master, especially once you knock him off Ruin, is definitely the first good non-giant boss.
Dungeon-wise, this game has the unfortunate distinction of following up Skyward Sword. That being said, it still holds its own to a solid degree; Twilight Cathedral is better than either of the Fire Dungeons of SS, Iron Canopy has a really cool aesthetic to it and some good puzzles, and The Black Throne is just fucking awesome. But The Hollow was just irritating as fuck, a standard issue Water Dungeon at best, and The Ashlands didn't so much make up a dungeon as a small handful of puzzles and a fuckload of easy fights.
All in all, it's a really freaking good game that just needs some polishing, especially in the combat. Good thing the sequel already looks fucking amazing.