Started with 8, I was blown away with the look and feel especially the special effects (compiz), Had never seen anything like it, it did crash a little bit, Zorin has had an Internal error.
Then 9 came out and fixed all that, I went Ultimate. Had learnt to work it a little better and get more out of it also. 10 arrived and thought I would get Ultimate again and have a little play for a while.
When 11 arrived, Ultimate again and learned some more tweaks and also started to find a few things no longer worked for a while, nothing major though.
9 rates as one of the best OS's I've ever had, so stable and reliable for me. I still use 9 on my 'test rig' from time to time. However 11 just had a few more bells and whistles and had moved forward from 9 and even though I did have a few pet peeves with 11 with creating USB sticks and a couple of other things...
Zorin OS 11 (Ultimate) is the best Zorin OS for me to date.
https://www.youtube.com/watch?v=fFATFIVeTBw12 Just went in a total new direction that just didn't do it for me, I still got Ultimate though and used it for about a month, had some issues that eventually got resolved but just didn't, and still don't like it. I now have 12 Lite on my shed PC for about a week so see what happens.
How about you zoringroup21?