For me, and of course this is just my personal opinion, based on my experience and preferences in bosses, there are a few contenders. I actually like a lot of the fights in the earlier part of this tier, maybe because we're used to them so they're more relaxed, but I like to think that it's because they have mechanics that are innovative without being gimmicky, and because the fights don't last forever. Some of the Terrace of Endless Spring fights seem to last about a week, and maybe it's because I'm healing, but that isn't a characteristic I particularly enjoy.
For me, as a shaman healer main, the best boss contenders are the following. Gara'jal the Spirit Binder, because the Spirit Realm health knockdowns, plus mana regen buffs, mean I can blow the top off the healing meter as mastery kicks in and mana becomes a non-issue. Pure /flexing, I know. And I must admit that it's pretty terrible on the raid finder.
Elegon is huge fun, although frustrating at times, and there's a real feeling of working together and accomplishing something when downing him outside the Raid Finder, and I enjoy the increasing abilities of the Spirit Kings, but Blade Lord Ta'yak's whirlwinds of entertainment take the cake. Others will find the mechanic frustrating and gimmicky, I totally see that, but for me, they're fun! Who doesn't want a bit of Frogger in their raid? Oh, everyone else? OK, fair enough.
Garalon's unforgiving nature makes for an interesting boss, but he lacks the sheer entertainment value of Ta'yak. Bashiok tweeted yesterday that he loves watching people get almost to the end then fail, and it is rather funny, except when they're that one player in your 10-man group who always falls at the final hurdle, or can't quite remember to get up onto the platform! Stay tuned for a follow up post on the worst bosses in tier 14 to hear more about Terrace of Endless Spring.
My no.1 fight for this tier is Imperial Vizier Zor'lok. I enjoy his mechanics, all of them, and just find the fight really entertaining every time I do it. It's so satisfying to pull off, when barely anyone takes any damage they don't need to, and to get him down. But enough about me, let's talk about you! Which boss gets your vote for being the best tier 14 has to offer?