Six or seven years ago, I may have gone with the sequels, as they were still coming out, and I would’ve pointed to the overall superior acting, darker tone, more practical effects/more seamless CGI, and the presence of Hamil/Ford/Fisher. But now, with over three years having passed since the end of the sequel trilogy, I find myself not feeling that much when I look back on that trilogy.

With the prequels, despite their numerous and obvious flaws(wooden acting, at times poor dialogue, questionable pacing, overuse of CGI, rushed plot movements, continuity errors with the OT), there are still things about them that excite me to this day, 24 years after TPM and 18 years after ROTS.

Despite the subpar execution, there IS a compelling story being told throughout the trilogy: the story of a Jedi falling to the dark side, and the story of a man manipulating a Democracy into kneecapping itself and handing him the power to transform it into a fascist dictatorship, while using said Jedi to accomplish this task. This story is compelling enough that it still motivates people to try to salvage/fix/improve it via fan edits two decades later. The story told in in the ST was compromised by the lack of a single vision at the top. I wonder if people will care enough about the ST story twenty years from now to still be making fan edits of it.
The Sequels showed many new worlds/planets, but some of them were obvious retreads of worlds we already know(there is little to distinguish Jakku and Pasaana from Tatooine, Crait[and to some extent Ahch-To] are love letters to Hoth, and Takodana[forest planet from TFA where Rey gets taken] feels a lot like Endor) and the ones that aren’t weren’t defined or fleshed out enough to be very memorable. The Prequels gave us a handful of new, immediately recognizable locations in SW lore. The forest planet of Naboo(home planet to Padme and Palps and site of the Trade Federation dispute), Coruscant(cyber-punk city planet, government capital, home of the Jedi), Kamino(obscure water planet where the Clone Army was created), Geonosis(Separatist headquarters), Mustafaar(fire planet, location of Obi-Wan/Anakin dual). Even the Wookie planet of Kashyyk and Utapu(where Obi-wan fights Grevious) are memorable. The world-building in the prequels is just much better. (To be fair, I will say the one really interesting and well-defined new planet from the ST was Canto Bright. It didn’t fit the TLJ, it felt like something from a different film, an unnecessary distraction, but it was a genuinely interesting world that I could totally see as the setting of D+ series or EU novels or something.)
The Prequels have a bunch of genuinely iconic visuals - the Pod Race, the Dual Of The Fates, Maul’s character design, Queen Amidala’s costumes, the silhouette of Anakin and Padme kissing as they’re moved into the arena on Geonosis, the Clone Army marching at the end of AOTC, Anakin with the two sabers on either side of Dooku’s head, the Order 66 montage, the Obi-Wan/Anakin Dual, the mask being put on Vader’s head for the first time, etc. Apart from any questionable dialogue or plot points any of these things might entail, they are visually, in terms of cinematography, classic, indelible images that stick in your(or at least my) mind. I struggle to think of any equally iconic visual moments from the ST, off the top of my head.
The Prequels introduced three indispensable pieces of music to the SW canon - Dual Of The Fates, Across The Stars(Anakin/Padme theme), and Battle Of Heroes. Anakin’s Betrayal and Padme’s Ruminations are good too. I honestly can’t, off the top of my head, think of any new, classic piece of music from the ST.
The Prequels introduced a handful of memorable new characters - Qui-gon is one of my favorite characters of the whole saga(and Neeson’s performance is the best of the prequels for me), Chancellor Palpatine is an interesting character when he’s not too over-the-top campy(I know he’s not really new, but we only saw The Emperor in ROTJ), and Maul - even though he’s a costume more than a character - is awesome. Also, the fact that people have complained for two decades about Christopher Lee/Dooku not getting more screen time is a good argument that he too was a good character. Finally, I may be in minority, but when the deleted scenes(addressing the senate, her family on Naboo, the negotiation with Dooku, the Rebel Alliance stuff in ROTS) are taken into consideration, I think Padme is a compelling character too. Even Windu - though there’s a little too much SLJ in him - plays an important role as the most hardline against Anakin and the conservative counterpoint to Qui-Gon’s maverick. I think the only genuinely memorable new character from the ST was Kylo and even he is very flawed, despite Driver’s great performance. Oscar Isaac, John Boyega, and Domhnall Gleeson were all wasted, imo.

I’m not as down on the Sequels as all that makes it sound, but with a few years’ distance, this is how I feel. OT over both though.