I’ve been using the Mac systems starting around 6.0.3 or so on a Mac Plus. By and large each version has added something interesting design wise – talented folks them Apple designers. I liked 7.5.5, up through 9.x was ok. The first time I booted the os X beta on my G3 233 (!) was like wow, look at them big fancy icons. The beta was useless but pretty. I’ll admit it, I like skeuomorphism though that’s not cool these days. Anyhow, for a new project I got a Mac Mini with Yosemite on it. Man, it’s dull and flat. It’s efficient I guess but it’s so, so, I don’t know, Soviet looking. I can’t imagine things will stay like this forever – I may be wrong but I think folks (and designers …) will eventually get tired of it and revert, at least a bit. Time will tell I guess.