Kings fall. As great as vog was, kings fall requires much more communication and teamwork, so it feels more like a raid than bog where most parts could be done with 2 people
Crota.
I feel like it had the most orginal and challenging mechanics. I'm also a casual, so being able to run all 3 characters in less than 2 hours was great.
I've been here since late yr 1 and never completed a raid. I've only gotten to totems on kf. Then I'm just kicked because no one's telling me what to do. So yeah. I don't have a favorite, never will, never will experience how fun a raid is (if it even is). I've honestly given up on ever completing, I'm always kicked off the fireteam and denied about 40 times. And besides, I'm probably the last xbox 360 user out there.
I used to sherpa players through Vault of Glass. Never had trouble getting a good squad together. Loved it.
I didn't enjoy Crota's End as much, but my fireteam came first, so I helped out.
Kingsfall seems to have brought out the least charitable players of any endgame activity (not counting Trials). Never completed it myself, and after so many failed attempts and crappy LFG fireteams, I have no desire to.
Vault of glass aways wins these, the huge scope and we'll put together mechanics, a mixture of bosses and other encounters leaves it at the top.
Kings fall is second imo, big scope but feels very narrow, only a single way to do certain parts,mess up once and it's a wipe, also past the aura it's just boss after boss
Crotas end only because it feels so small, thrall maze is cool, bridge is great but they're both over quickly and then it's just deathsinger and the boss, still enjoyed 3 manning it 3× per week but yeah, more of a huge strike then a raid