Your option seems to be:

-Nexus 5 (All options, except microSD/removable battery. You might be able to run native ubuntu or chroot it, or port Mer if you like)

-SGS4 (Not as good as the Nexus 5. Has all options you need. Slight chance of Chroot/Native/Mer.)

...otherwise the options seem to be:
- Another N9 (Pretty much an obsolete choice now)
- N900 (Somewhat of a compromised downgrade)
- SailOS (The only* linux device out there, but much of a let-down)

I wouldn't consider BBX, FirefoxOS, UbuntuPhone and Tizen as choices.