I have an annex that syncs my personal files on all my computers. It works great. Phones are different.

For one, everything's a bit slower to sync, there's battery considerations, and I just don't need every last old file on my phone. Then there's some files I explicitly don't want on my phone in case it gets lost, like family pictures, passport scans, or private keys.

But I still want photos, videos and voice recordings I make on my phone to be synced to my server. A transfer repo would work, but I want to keep them. Then there's my PDF book collection; that would certainly be nice to always have around in case I have half on hour on a bus. And my music collection ought to be around as well.

So I came up with this solution, and I'm very happy with it.

    include=Music/* or include=Books/* or present

This will sync my music and book collections to my phone whenever I add something new on my computers, and it will sync and keep anything I add to the annex on my phone. Best of all worlds! Impressed how flexible preferred content is. More full-sync folders can be added like this: 

    include=Music/* or include=Books/* or include = Notes/* or present

To add them, I first had to figure out the uuid of my phone repo. So I added a new tab on android, and did

    cd /sdcard/annex
    git config annex.uuid

Then I went to one of my computers, and did

    git annex vicfg

And changed the line

    content [phone-uuid] = standard

to

    content [phone-uuid] = include=Music/* or include=Books/* or Notes/* or present

and commented out

    #group [phone-uuid] = client

And waited for it to sync.