I've seen some other people do this trend, so I thought I would go through my favorite/least favorite sets that came to the EN and JP servers this year! This is mostly just based on the card art and how memorable I think the sets/costumes are.
Credit to akaoi, missa-chan, chomama, and kasei_, who I saw do this trend/a variation first !! Graphics were made by me
Popipa

Favorite: Poppin' Halloween Parade
Least Favorite: Message for You
I feel like Popipa had really solid sets this year in both servers, Message for You was just the most forgettable.
Afterglow

Favorite: Cycling Seasons, Fresh Skies
Least Favorite: The Repressed Flame which Burns the Sky
Personally, I don't like the posing of the cards from Repressed Flame and the costumes aren't my favorite by any means.
Pasupare

Favorite: Devotedly Towards my Dreams
Least Favorite: Brighter Brighter
There's just something about the more casual pasupare costumes (like winter sky marche eve/chisato) that really appeal to me.
I'm not a big fan of the costumes from brighter brighter and I feel like both Maya's untrained and trained card art just looks Off. Overall very forgettable.
Roselia

Favorite: Noble Rose (Bearing Flowers)
Least Favorite: Prelude Replay
The lighting of the Bearing Flowers set is so beautiful, genuinely one of my dream sets to finish.
It was actually really hard to decide on a Roselia set I didn't like this year. In the end I decided to be a bit nitpicky and the only reason I chose Prelude Replay is because Rinko's face in the trained art has always looked off to me.
Hello, Happy World!

Favorite: A Summer's Night, Poems Across the Water
Least Favorite: Hello, Happy World's Smiley Summer Vacation
Personally I just thought Smiley Summer Vacation was a forgettable HHW set and tbh I really only like Kanon's card :/ I definitely understand why a lot of people did like the set tho
Mixed Events (JP)

Favorite: Prismatic Duo
Least Favorite: Viva la Live!
Usually I'm not a fan of Christmas events but Prismatic Duo was absolutely beautiful. I think about the lighting on Hina's card and Rinko's untrained card every day. Beautiful costumes, beautiful card art.
Viva la Live! just had awkward posing and anatomy imo. Most of the untrained and trained art just looks slightly off to me, especially Yukina and Kasumi's trained cards. The costumes are also rather forgettable.
Mixed Events (EN)

Favorite: Shadow of Days Past Remain
Least Favorite: A Day off Downtown
I don't know why but I'm just obsessed with Musketeer Kaochisa. I also really like Himari's untrained card. Very good costumes overall
A Day off Downtown was just a forgettable set imo, I like Hagumi's costume but I'm not a fan of the others and Tomoe's card is genuinely one of my least favorites overall :/ She deserves better