I'd have to say I never liked Amber Shaper, then again I never bothered to learn it properly.
Lei Shi was pretty garbage. An at the time relatively new way to play a tank (i.e. Active Mitigation), so let's throw out a boss who goes invincible so you can't generate your resource for Active Mitigation, but it still attacks you.
Honorable mention goes to several bosses due to the sheer number of guilds that were stuck on them: Horridon, Garalon, Nazgrim, and Stone Guard of all things.
Lei Shi, Garalon and Dark Animus. I have had nightmares with the last one..
Lei Shi and Galakras.
Both very, very annoying in their own way.
Lei Shi and Unsok were awesome fights! The worst encouter was by far HC Dark Animus. One little mistake (like healer aggoed another add) lead to wipe.
Why is everyone hating on Lei Shi? Once we got the CC'ing down it was easy. We cleared ToES the first night we were there.
When I think of the worst boss of MoP, I can't help but think Garalon. Mechanically it was pretty interesting but it was always terribly balanced and just not a good time for anyone. It didn't help that passing off the pheromone worked right like 75% of the time. And that super tight enrage timer.
Also Heroic Ji-kun. Fuck travelling in 3D space.
You just lost The Game
HC Seigecrafter. Our belt team still has ulcers. I think they invested in Tums...
for me it was heroic amber shaper, but i never got into soo heroics.
Indeed, this is about bad fights not difficult fights. Although some other people in the thread seemed to have misunderstood that
Lei Shi was just booooooooooorrrring. So much time spent unable to actually hit her properly. You basically got a few seconds hitting her then she vanishes, then she comes back and you get a few seconds then nope, time to deal with adds. By the time you get the adds down you get a few more seconds then the stupid wind thing. Then more shields, more adds, more vanish, more wind... oh god make it stop.
Galakras (I hate bosses where you have to fight waves of adds..its why I still don't like Hyjal). Immerseus because its just flat out boring even on heroic mode.
A FUN fight is Heroic Klaxxi believe it or not.
MSV - I don't know, probably Will of the Emperor for the dance mechanic and for taking for-freaking-ever.
HoF - I'll jump on the bandwagon and say Amber-Shaper as well. I would have hated it less if my raid wasn't using a 'stack tons of puddles' strategy which meant that even getting to the point where people could practice the vehicle was mind-numbingly boring.
ToES - Lei Shi. It never failed, that whatever that encounter could do to be the most frustrating, it'd do it.
ToT - I'm going to go with Tortos. I didn't care for a few others, but Tortos is the one that actively pissed me off.
SoO - Tie between Immerseus and Galakras for the same reason -- boredom.
Immerseus is a nerfed version of Molten core Rag.... that fight is sooooooooooooo boring. Lei Shi is a fight that is cool once or twice and then quickly moves to the "omg this fight again" pile.
The two crappiest for me were BY FAR Garalon and Dark Shaman.
Lei Shi, for all the reasons above. Lei Shen because it drives me nuts to be moved around in a fight when I don't want to be. Dark Shamans because it was a wipe fest for the first month or so (but the last 11 have been fine! ). Garrosh just because he's the pug killer despite not being a very hard fight at all.
Who ever created Lei Shi should be off the dev team.
Lei Shi and Immerseus because I hate bosses where you have to wait for something or have a boring task until you can continue.
Atoms are liars, they make up everything!