Man I really loved MeeGo, I was in my early teens when I got the N9 specifically because it was such a beautiful experiment from Nokia. Amoled display, MeeGo os and the polycarbonate shell. The phone was hot garbage technically, would over heat had 0 apps and had idle battery times worse than a cup of tea left out on a cold day. However the phone was such a work of art I could accept just about any flaw.
Right after that I got a Blackberry Z10 and there's just something about the multitasking UI in both of these OSs' that just felt like it was the right way of doing it.
Blackberry OS 10 and MeeGo where so wonderful, I truly had a rich experience of mobile phone OSs' growing up.
I'm not sure about Jolla as much though. Like I enjoy having this additional option but I wished they digged deeper into features other than enhanced privacy. Not that I'm complaining, I enjoy having enhanced privacy but if they added more productivity features like the Blackberry Hub.
Nokia N9 still has the most modern and refined user interface, 15 years after being discontinued:
https://www.youtube.com/watch?v=iCFNXhiFnKY