Multi window/split screen -AFAIK you can only do this on iPad
custom home screen/launcher: the icons on a grid both bores and overwhelms me, so I use a minimalist launcher with a few shortcuts and app drawer for the rest
removable SD card. Sure, storage is getting better on phones, but the ability to pop a 2TB micro SD in my phone and keep offline copies of whatever I like for times I have no service is absolutely crucial to me (SD slot depends on what phone you have ofc, some manufacturers ditched it)
home screen widgets
notifications are superior on android
USB 3.0 speed data transfer with no additional software, to any device that can accept a USB stick
third party apps and app stores
being able to install apps I develop for my own personal use without paying for a developer account, having to list it on the store, or having to reinstall it every few weeks
ability to run Firefox with extensions
multiple accounts for the same app without needing to log in and out
USB OTG
game emulators
can safely browse tor

Depending on what model and manufacturer you go with,