Ahhhh I wish I could pick more than 2 options to vote on.
TRR is just the overall best imo with phenomenal set cohesion, stylized artwork, the return of dark Pokemon, nostalgic callbacks to the original Team Rocket set, and arguably the best set of gold stars.
Sandstorm was my second pick because its desert/ruins theme is just so tight. The set also has the best overall regular card artwork across all the EX sets with the iconic e-reader borders. It’s like collecting a mini-Skyridge for a fraction of the price.
Delta Species and Unseen Forces were also sets I wanted to vote for but the above two just take the cake.
Dragon Frontiers all the way. I’ve talked about this in length in other threads so to summarize here: the Pokemon, art, themes, and design choices in this set are second to none to me. Delta species is such a great mechanic and I believe its climax was here. Its also the set I have the most history with(CG, DF, and PK are essentially my Base, Jungle, Fossil) so it will always be special to me
Its tough to pick between the first 3 sets, they remind me so much of the late wotc sets and are themed to perfection. I picked sandstorm last time, so for the lols I’ll pick dragon this time. All 3 are about the same to me
I know people love Rocket Returns but something about it just doesn’t hit for me. I think it’s that all the ex cards are dark type so in my mind they don’t feel as distinct.
That said, I completely understand why people rate it so much. There are some fantastic individual cards and the theme is very strong.
My choices were Unseen Forces and Crystal Guardians, but it was close. The huge caveat with Unseen Forces is the stolen gold stars; they really bring it down imo.