Personally, I find the discussion about the OS to be the most interesting. But I have to admit that I am a bit surprised by the apparent enthusiasm on Sailfish.
I can very much understand the criticism on the 'google-ness' of stock Android. That leaves CyanogenMod, Firefox, Sailfish and Ubuntu (at least to my knowledge) as only serious alternatives.
Ubuntu is very promising, but still far from being ready for a port to Fairphone - at least, this is the feeling I get when I read the forums where users discuss their experiences.Ubuntu is extremely interesting, mostly because of its promise to converge with the desktop version (and the Ubuntu software store, think of downloading all that amazing software on your telephone!). Still, it has been promising for the last two years. I have no idea how much time (half a year, 1 year, 2 years, even more?) Ubuntu needs to become ready for a 'regular' user.
Firefox is open and on the other hand is being used by thousands of 'regular' users. The main thing users seem to complain about is the general lack of available apps and most of all whatsapp. If you're willing to go without whatsapp and all the weather, traffic, geo and chat-apps, it is a real alternative. To my knowledge, it is not possible to download apps from 'alternative' locations (like F-Droid f.e.)
CyanogenMod is (almost completely) open source, community driven and is being used by many users, of which many are focused on privacy. Also, most of the users have installed CM after wiping the original OS. As a consequence, there is a lot of documentation on porting CM to different telephones. Biggest advantage in comparison to Ubuntu and Firefox: one can install all android-markets (google, F-Droid and others). So one can use Whatsapp!
Sailfish is in a similar position as CyanogenMod. The UI is closed sourced, the rest is open. Its community driven and is being sold already for a longer period to 'regular' users. One can also install Android-apps through its compatibility-layer. As a disadvantage to CyanogenMod, Sailfish doesn't seem to have a large track-record of being ported to other telephones.
In my opinion, Sailfish doesn't have any advantages over CyanogenMod. Both are mostly, but not completely open source, both can install apps from alternative android-marketplaces, and both seem to be ready for the 'regular' users. The user-base of CM seems to be bigger and there is a lot of documentation on porting to other machines.
My question is therefore, could anybody please explain the enthusiasm for Sailfish, in comparison to CM? Or am I missing obvious things?