I liked the third Droguza battle in Arc the Lad: Twilight of the Spirits because I felt it provided a nice challenge even when decently leveled -- not over-leveled, but not under-leveled, either. It's actually the first boss I encountered that I had to try over and over again when I first got the game (the same for Demon Droguza, the next boss) because I wasn't properly leveled and / or equipped (I don't really remember, though). Skip to 32:44:
Bad Girl - No More Heroes Ok, firstly can I just say DAT BOSS BATTLE THEME - seriously, it's like my favourite boss theme from any video game. It gets me pumped. Anyway, hers is my favourite boss battle because not only is she a fierce loli with a baseball bat who launches half-naked men, bound and gagged S&M style, towards you, but it's a difficult and lengthy battle, and if you don't strategize properly she will destroy you. I'd like to know just how many people fell for the part where you've almost beaten her, she lowers her baseball bat and leans forward in exhaustion, then you run in to finish her off and she insta kills you. Idk I like her bitchy character personality and its always a fight I enjoy coming back to. Suda bosses are the best.
Spoiler: Breath of Fire 3 This is largely just because this was among the first games I've played, but Myria just has special place for me here. She is just so calm and caring through so much of the story but you slowly realize that she is too overbearing in her attempt to care for you and have to fight back. Having not played any game with deicide, the very concept of this fight rattled me. I mean as like a 6 year old, you try telling her that you have to fight her because she is overprotective. And then... I still can't beat her without cheesing it in some way or another. I'll need to think more about one that goes beyond nostalgia.
Xemnas in KH3D. Not only does the battle have a very epic remix of my favorite battle theme, Darkness of the Unknown, but I don't think have had so many feels during a battle ever. The revelations about Nobodies and Xehanort's true plans sent so many feelings in my mind flying around. In fact, I had so many feels that my body was literally shaking when playing through the battle the first time. Seeing Sora stick up for all the characters who've been f***ed up by Xehanort at one point really made me respect Sora a lot during that moment (and this is coming from someone who isn't a huge fan of Sora). So when fighting the battle with Xemnas, for me it was essentially payback for the bad things that happened to characters I love, like Roxas, Axel, Xion, Terra, Aqua, and Ventus. Also, it helped that Xemnas was being a total badass during the whole battle.
Xigbar all around, I absolutely love the way you fight him and the way you can use warp snipe with Sora to beat him, out of all the ORG bosses and to be honest all Video game bosses I personally love this fight JUST for the reaction commands but also I'm torn between this and Xemnas' battle because of all the amazing reaction commands. :C
My favorite boss battle of all time? Hm..... HEY, YOU'RE NOT A HUMAN ARE YOU? I love this boss fight. It's fun, it's challenging, and it's always surprising you. Everything you think you can do, you can do. It's kind of a good surmise of the entire game. Spoiler: Runners up Prince Vorkken Demon Lord Ghirahim Vamp The Koopa Bros Kraid Meta Ridley Magus Ganondorf
It's pretty tough picking just one....so I won't: Devil May Cry 3 - Vergil Ain't NOTHIN' as sweet as fighting your twin brother, who shares many of your half-demon, half-human traits and abilities. You both have Devil Trigger, you both have demonic weaponry, and you both want to see the other fail. Batman: Arkham City - Mr. Freeze I was going to put Scarecrow from Arkham Asylum, but he's less of a fight and more of a level. Mr. Freeze, on the other hand, forces you to play a boss fight differently than most others: hiding and strategizing. Metroid Prime - Meta Ridley A first-person battle against a metallic space pirate dragon who fires lasers and missiles at you while you use the Phazon Suit and your arsenal. 'Nuff said. Spoiler: Metal Gear Solid 4 Metal Gear REX Vs. Metal Gear RAY It's pretty much like a freaking Kaiju battle using mecha dinosaurs. Spoiler: Okami Yami The way you start the battle stripped of all of your power and have to fight back to gain it, coupled with the music and the motifs of light and darkness being used pretty literally, made this just plain epic
Mysterious Figure. Seriously though, most of the bosses in Prince of Persia (2008) were great. I can't really think of many boss fights off the top of my head that were truly amazing. I know I've seen them but I can't remember them... I guess my favorites would be Grigori(the Dragon) in Dragon's Dogma or Daimon from Dark Arisen. Grigori is probably one of the only proper dragon battles in video game history.
The other main character in Muramasa: Rebirth It's not REALLY the main boss of the game, but still, it was so much fun fighting off against one another as he battles felt tight, epic, and just an all round enjoyment
KH2 Xemans Final Battle A lengthy boss battle with a lot of different elements included. Taking control of Riku was defintely the defintely the highlight of it all.