Anything metro
All play apps except market
Goole drive, maps, keep, photos, hangouts and chrome
Calculator, calendar, non Google email
You will loose some services (I.e. third party email.)
Remember to dump data and cache of anything you delete so you don't leave dead space (memory filled with useless stuff).
Also, I would use titanium backup (free) to check the listed status of apps and avoid deleting anything that shows up red