The main one I use is Jotterpad. While iOS has an excess of "write in Markdown, save in Dropbox" apps, Android has comparatively few that don't require at least some assembly (syncing with Dropbox separately) and this is by far the most polished IMO.
Inkredible - for notes that are scribbled instead of typed. Squid is cool too but I won't use it heavily enough to justify a subscription.
OneNote - My job is a Microsoft shop. Sadly they don't let you install this from the Play Store any more, have to sideload it.
Netflix, Spectrum TV, HBO Go, Showtime Anytime - Gotta have entertainment, and these work better than the web.
JuiceSSH - granted the SSH app for Chrome OS is nice and well integrated but I've had this for a long while on Android so why not.
Termux - Mini linux without using dev mode. Usually I just ssh to a server, but it's still nice to have a local Emacs once in a while.
Hearthstone, XCom Enemy Within - again, gotta have entertainment.
Google Play Books - better than web version.
Some PDF reader I forget the name of -- reading my stash of RPGs and technical books.
And that's why I like the Chromebook Plus as an Android tablet that happens to have a full browser too. :)
Only for Android, but JotterPad by far.
Edit: some features I use:
I've gone through just about all the major mobile writing apps, and JotterPad is marvelous, especially with an external keyboard. Sometimes I write on my phone even though the computer's available, just because I love the minimal interface and no distractions.