hello friends! new(ish)!
Portables
This dongle is a 
Smartphones
Personal tracking devices.
Android
A Java VM (Dalvkit) running on top of the Linux kernel, comes with Google if you don't set it free. Needs some debloating but still the best bang for buck. See Android Ricing for unlocking and tweaking. Nexus is the popular flagship line that comes with OTA updates as soon as they are released.
iPhone
Jailbreak the Unix-based iOS with http://evasi0n.com/.
Jolla
The phone running Sailfish OS, a partially (the underlying is opensource, the UI is partially proprietary) open source operating system based on Meego developed by fired Finns after Microsoft jewed Nokia to death. Meego in turn was based on Maemo, the Debian-based N900 OS. Capable of having Android apps installed.
Firefox
Fully open source OS made by Mozilla, and based on Firefox/Gecko (the rendering engine). It uses the same kernel used by Android.
There are some phones running it, officially:
Windows Phone
Mostly Lumia by Nokia. Very limited number of apps (<100).
Tizen
Soon to come Meego fork by Intel on Samsung phones.
Ubuntu Touch
Opensource operative system developer by Canonical, created to have the same look&feel as Unity on the desktop. While it used to share the kernel/graphical stack with Android, now it uses it's own stack, sporting Mir as the graphical system (instead of SurfaceFlinger).
It currently run, albeit buggy/glitchy, on some Android phones/tablets, like the Galaxy Nexus, the Nexus 4, the Nexus 7 and the Nexus 10.
Ubuntu Touch is famous for being the operative system of the Ubuntu Edge, the phone for which Canonical had an indiegogo campaign. While the campaign failed, Ubuntu Touch is still actively developed.
Tablets
Nvidia
Tegra Note is basically a highly powerful tablet. Everything else about it is poorfaggotry however.
Nexus 7 has stock KitKat android, a great screen and is sleek and fast. Also comes with goodies like OTA updates. Beware if you care about software freedom because the Nexus 7 is tied to Google (obviously.)