I’m also a Super fan. It was far from perfect but comparing it to GT is nonsense. GT has zero redeeming factors. Super had quite a few good storylines, characters, transformations, etc.
It's a lot closer to GT in overall quality than it is to Z, IMO. The attempt at storytelling in Super is really cringe-worthy and dumb-founding (GT is as well), and I would argue that GT is more structurally sound and feels less like it's just being made up on the spot (even though the execution is pretty awful), although Super does do a better job of understanding the characters/charm/attitude of the show than GT and is better at fan-service, I suppose (I'm guessing that's ultimately why people like it more). Super's kind of like an entire series that feels like weak filler/tributes to Z (even the main arcs). Neither are great in terms of animation/art/aesthetic, but the lows in Super are more laughably ugly and the consistency is all over the map (sometimes they pull out all the stops production-value-wise, like for the latest arc, but even then, the art looks pretty off/wonky to me). GT's art looks dissimilar to Z, but it has more of a consistent unique, and cohesive style of its own than Super does (whereas to me, Super's art looks like fanart of varying levels of quality that nobody can get quite right).
Overall, I would say that GT has the feel of a bad/soulless show made by people in the industry who barely have familiarity with the series and are just basing it off their notes or something, whereas Super feels like a bad show made, written, and drawn by the fans. Obviously that's not the case literally, but they give off that vibe to me.
Dragonball and Dragonball Z on the other hand are cohesive, memorable, and consistent shows with real personality/charm, effective storytelling structure, and a legitimately great aesthetic, despite the show's clear flaws/irreverence/neglect for things that probably matter.
I do legitimately like and appreciate the closing and send-off at the end of the most recent arc of Super, though. But that's kind of the only thing that stands out to me.