I'm torn between Maiden and Sisters. Maiden brings me back to Thadius in Naxx, in many ways. And Sisters, like Maiden, is all about personal responsibility.
I'm rather fond of Maiden. It can be a bit stressful (especially in pugs), but it's really rewarding once you work out all the kinks.
Sisters of the Moon. Because it's a really beautiful chaos, and I really enjoyed it when I kill them the first time.
Fallen Avatar was my favorite. He's basically a dps check, but there's so much fun stuff going on that he's not a boring one.
Maiden, because it's a lot of movement and fun (bomb). It's not a boring encounter.
Love the Inquisition fight, primarily because it has made my friends rage so hard. I might find it funny that a solid dispersment fight like that can make my hard-core raider friends rage so hard, lol
I love Heroic Kil'jaeden cause i have over100 wipes and trying to get Curve xD
Demonic Inquisition because it's a nice trying to figure out the mechanic on the first week & was refreshing.
Maiden, cause of one player can crit her for 60M they want to change whole spec.
Maiden, very funny trys in my guild :D
Favourite boss fight is actually Maiden.Lot of personal responsibility, but if everyone just pays attention, it becomes such an easy encounter.
Mistress Sassz'ine, I like the setting, her summons are pretty cool and all phases have something to watch out for.
The fallen Avatar ´cause lore and hype! Lol
While I think the 'moon floor's mechanic for sisters is cool, I think Maiden of Vigilance's guitar hero mechanic is the best!
Maiden - ups the ante compared to the previous bosses and is for the most part an enjoyable fight.
maiden! the ulduar/titan theme and the orb minigame is so much fun!
Heroic Mistress just because of the insanity involved when ALL of her abilities are piling up at once. Hands down my favorite fight.
Kil'Jaeden! I've been waiting to fight him again for so long :P
I like all the new fights, ToS to me seems really well thought out. If I had to pick one fight in particular; I would have to pick Kil'Jaden, in this fight everyone is constant needing to do things. It requires people to soak meteors, healers need to be moving around a lot because during the second intermission the darkness will kill people if they soak a meteor prior to entering the darkness phase. It has actually killed me a couple times now. I really like the KJ fight.
KJ, because this time he isn't just a torso.