AKAIK Jolla is more open. Its more like a Linux distro than Android. I want something else than trying custom Android ROMs. I want to be fully in control of my device.
The entire UI (all the code in the stack from Mer up) is proprietary. Sailfish is less open than Android. Atleast AOSP is a fully functional OS you can run on your phone (though dramatically less functional than when you include the Google binaries).