A slowly dying 64GB 4S to 128GB regular 6. Seriously my phone almost died on me when I tried to back it up just now and its battery life is maybe 4 hours at this point.
I'm going from the Droid Razr Maxx to the 6 Plus 128GB.
Worst timing possible. Just updated OS X and now my MacBook is only showing a black screen. I'll have a brand new phone and won't be able to sync and going into an Apple Store won't be fun right now.
5 - 16gb to a 6 -64gb. I felt guilty for giving my girlfriend my 16GB 5, so I found a deal on ebay for $460 for a 5s 32mb, and I'll sell the 4s and 5 that I have now. I have way too many of these phones!