Honestly if 16gb works for you...great, however shame on Apple.
4K recording, iMovie, Pages, GarageBand, Numbers, Live Photos, HDR, etc on a 16gb device? Obviously I'm not daft enough to not see what Apple is doing. They do crap like this across their product lines (4K iMac with iMovie and a 5200rpm HDD), to get you to upgrade.
I find this to be a shady business practice and ends up taking advantage of people that don't know any better. The specs the base models get are so low that it forces your hand to upgrade, assuming you know better. This way Apple products don't look more expensive then the competition.
For example, if you use FCPX on a Mac you generally know the specs you need to use that software so you buy a Mac accordingly. However if you buy an iPhone with iMovie and GarageBand on it you don't expect run out of space with a couple of projects.
Now to play devils advocate with myself on price. iOS and OS X includes some pretty good software right out of the box. For my needs iMovie, GarageBand, pages, and numbers are great and otherwise free. Soooo...yeah...