128. I had an Iphone 5 with 32gb, and was struggilng with space for one year. I guessed It'd be the same with the 64gb eventually, so I said what the hell.
Ordered Space Gray iPhone 6 64GB off AT&T website - personal everyday phone
Bought Silver iPhone 6 Plus 16GB with personal pickup - design testing and media device. I then realized 16GB was really only 10GB out of box and 5GB after installing a few apps. Not enough space to store even 1 iTunes HD movie.
Immediately exchanged 16GB iPhone 6 Plus with a Space Gray iPhone 6 Plus 128GB - I wanted 64GB, but they only had 128 which I am fine with.
I have the 32GB version of the iPhone 5. That one is getting a little full. 64GB has been my plan but after looking at inventory, I might just spend the extra $100. to get a 128GB instead of waiting for a 64 to become available.
edit - I did spend the $100.00 to get the 128GB version. I like instant gratification and I had to wait to long to make this happen!
64GB
Last week I run out of space on my iPhone (5 with 16GB) while I was taking pics at a party and I had to remove apps frantically to gain some space.
No more 16GB models for me, if they'll double the storage in the cheapest model I think I'll go for that since 32GB are enough for me.
16 GB here, ... cloud computing and cheaper data plans made this a no brainer to me!
Dealing with tons of TB's these days feels so 2000, ... at least to me.
Reduce and simplify your life
... on a sidenote: did step down to 128GB worth of storage on my new MacBook Pro too - never had run into issues so far. Guess heavy Dropbox using here