Here's a few reasons why I like Jolla and Sailfish:

I like the gestures. I like the pulley menus, the one hand - friendly operation. I like the ambience thing, the aesthetic of it.
I like that I can modify things I don't like just by looking around and playing with .qml files (e.g. I have brought back the refresh action on the browser cover). While we're at that, I like that I "rooted" the phone just by enabling developer mode in stock settings.

So there, some reasons for you. Now if you're going to try to refute them all one by one for no apparent reason, just know that I can do the same for your OS of choice

P.S. And about the whole open / closed source argument. Indeed one can argue that Sailfish is not all that more open than some Android flavor but are you really comparing Jolla to Google? The first is just a mobile OS company, the second is everything from a search engine to artificial intelligence and then some. It's just not wise to let a company that big control and know about every single aspect of your life, even if the only alternative is letting a lot of other smaller companies in. When Jolla become big and they still haven't open-sourced the code, then I can worry about them as well.