GT had a slow start for me. I know what they were going for but the jump from 0 to 100 was very obvious. They needed to cut down on Trunk's adventuring and get Goku back to being the show stealer. When the show started getting good, I felt that it went too fast. It was rushed in comparison to what happened previously in Dragon Ball and DBZ.
As for Super, I enjoyed the introduction of new higher beings and power levels. The Future Trunks saga is one of my all time favorites now. I know a lot of people didn't like DBS based more so on the ToP than anything. It was drawn out where it shouldn't have been and sped up when they could have slowed it down and offered more depth.
Out of the two, I would say Super was better overall. GT had a faster ending that lacked substance for me but Super had a slower ending that felt too dragged out at times but I found more enjoyment with the expansion of the universes and new diverse characters.
Now im a fan of GT always been but when comparing it to Super to me thier is no comparison. Super has great fight scenes and all around great story telling even though some parts were dragged out . If we comparing GT to orginal DB or DBZ then the argument gets a little more technical
I'm a fan of certain aspects of GT surrounding character development mostly relative to Goku. As we all know GT stands for Goku Time. You have to give it to Super for world building and expanding the lore of Dragon Ball. Now we have an entire multiverse with endless characters to explore. One thing I want to see is them MAKE SUPER SAIYAN 4 GREAT AGAIN! It's going to happen, mark my words.