I did grow a few big accounts, to be honest. vines/fail videos doing the best job here on Instagram.
For everyone that saying Luxury, it's also nice.
But.. Let me say you have a luxury account with 2m followers, most of them only hit 20-50k likes and arround the 100-300 comments. (I say most, of course there some nice accounts between them)
But an average 2m vine account gets like 50k likes, and 1k comments + (Of course, average. there a lot of noob accounts too)
So i would say, if you want to get a lot of activity, Do vines. Or Luxury. Both doing great.
Sexy woman etc doing good too, but hard to sell shout outs.