As I have big wrists and my eyes aren't getting better, I like a larger screen a lot. But for me, the most important update might be, that the screen now updates every second instead of every minute in the "inactive" mode. I do use the seconds display of any watch a lot when timing short things, especially when cooking. Whenever I want to watch the seconds, with my current watch I have to keep shaking my wrist to keep it active. Having a seconds display all the time is the big step to make it a real watch. I hope they also add a digital watch face with seconds display.
I would have like a bit better run time - as the CPU is getting more efficient, I hope Apple is downplaying any enhancements. With my 7 series Apple watch I do still get 24 hours of run time (wearing it at night) after 3 years, so it is just sufficient. But a bit more would add safety margin.
A future Ultra 3 would be tempting with a longer run time and especially the red "night vision" watch face. I would so much like to have it on the plain Apple watch - clearly that is an artificial limitation.