Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.
iPad mini2 - 9.3.2
Earlier I was on 7.1.2. It was about 1.5x faster than 9.3.2 Also the battery lasted almost 2x longer.
But it had no bluetooth, fewer sharing options and many apps required iOS 8 or above. So I got 9.3.2
 
I've stayed on 8.4 for jb. Wish I could upgrade to 9.x and jb, just so I can get some apps that require 9.0 and above.


iPhone 6 on 8.4 jb

iPad Air 2 on 9.3.2

iPhone 4S on 8.4 jb that I don't use
 
iPhone 5s Stock iOS 9.3.2 (updated from iOS 8.4 JB because of watchOS 2 speed/feature improvments)

Apple Watch SS obviously

iPad 2 (yes 2:nd gen) iOS 8.4 JB
iPad mini 2 iOS 8.4 JB
 
iPhone 6S: JB on 9.0
iPad Mini 4: JB on 9.1

Would not upgrade for the world (unless somehow a JB is released for iOS 10, which is looking pretty doubtful...)
 
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.