Let's see...
I prefer Crystal the 90s anime. The 90s anime has
very strong moments that far surpass almost anything in Crystal, but that's the thing, they're
moments and you need to wade through a sea of repetitive monster-of-the-day with cute but samey interactions over and over to get to them. Crystal is more direct, faster, more consistent, and pays more attention to the lore, and that's what I like the most in Sailor Moon.
This might be the hottest of them all and I know I might be the only one who thinks this, but I think S is overrated. People always talk about how it's dark and mature and all that and yes, it has dark and mature
moments but most of the season has the same usual cute adventures from every other season, only now with what feels like the goofiest monsters of the day they could come up with. I think Classic and R were darker.
While I like Infinity, it's also my least favorite arc compared to the rest because its villains feel too disconnected from the series lore. Dark Kingdom explores the past, Black Moon the future, Dead Moon the inner conflict and Shadow Galactica the cosmic conflict that ties everything together. Meanwhile, the Death Busters are random aliens that are only related to the real meat of the story (Saturn) by total coincidence. I've tried to look for anything to tie them to the overreaching lore and the only thing I found is that they arrived on Earth due to the distortion in the Sankakusu/Mugenzu area, which Saturn says is where Crystal Tokyo will be located in the future, so there
is a faint link to the lore but it isn't explored and they still feel like a random excuse to have the Outers show up.
Black Moon and Stars are my favorite arcs. I know Stars is vague and strange but it really elevates the series and its implications for the lore are fascinating. Black Moon are very interesting villains and while the time travel is wonky it is worth it for me because I love how it explores the future of the world.
In the 90s anime, R is my favorite season. It's strange because it gives the shaft to everything I liked about Black Moon in the manga, but it makes up for it by developing other interesting things like the character dynamics and even the Hell Tree arc as the fallout for the amazing Classic finale (my favorite part of the entire series, although I feel that as a whole R is stronger than Classic).
I like the Senshi and Shitennou pairing and I never understood why people reacted to it as if it was the worst thing ever. Is it convenient and corny, sure, but this is Sailor Moon, it feels right at home with the rest of Dark Kingdom. The payoff was dumb and almost nonexistent, but in and of itself the pairing isn't bad.
Yuichiro is just as if not more attractive than Mamoru
This shouldn't be an unpopular opinion! He's the best guy in the series and while manga Mamoru is good, I think Yuichiro's style is cooler.