I like the Plasma redesign - sides have been shaved a bit so that it's slimmer, thus easier to grip. Not sure if it affects drop protection height, as UAG no longer advertises height anymore. They just advertise Military drop-test standards (MIL STD 810G 516.6). Otterbox and Mous don't advertise height either, and they've also been getting thinner on the sides. I also like the black UAG logo as opposed to the old silver ones.
Thinking of getting a Monarch as well. Trying to decide between Carbon Fibre and Crimson (I currently have an all black one on my S10+, so looking for something different). I like the logo placement at the bottom now. Case looks great.
And I agree, UAG is ole' reliable. You know that you're getting an all-around top tier experience with regards to good protection, buttons, comfort and grip.