My solution is not using a smartphone at all - I don't consider the
merging of phone and tablet as done in a reasonably safe way, and I
don't like the idea of bugging my bedroom myself.
It will be interesting to see what develops with FirefoxOS.
The problem with Android, while the base OS might be really good, the culture of Android is a platform to distribute closed source software to generate a profit, either through advertising or app sales, for Google and the software authors. Why else would software authors right software if they can't make money is the mindset. Even free apps written for public use (e.g. public transport) with public money are closed source.
Closed source software means you have to trust the software author that it does what they say it does, and nothing else. Yes, permission model is suppose to help this, in a practical sense I suspect they are of limited value. How many people really check the permissions and refuse to install an app just because the list looks excessive? Closed source software means that the code is probably of poor quality also [1].
In the past I have seen arguments with Android software developers along the lines of "Why do you need permission X?" "To allow debugging." "No you don't!" <no response>. I suspect many authors blindly add permissions because they eliminate the apparent errors, without actually considering if the permission is really required or not.
Also, there is no good catalogue of open source Android software for example (F-Droid last I checked was missing a number of open source applications I commonly use).
Notes:
[1] For that matter, I suspect there are Android applications that don't save data when the app is moved to the background, resulting in risk of data loss. e.g. incoming phone call. Android is free to kill background apps without notice, this is (and probably always has been) clearly documented. People continue to get this wrong however. Any app that has a "save" button is suspect, I think, although some apps will do the right thing. e.g. one I am testing now appears to do a silent implied save when you put it into the background, which is OK, just not completely expected.