Super is not only far better than GT, but combines the best of Dragon Ball and Z and gets rid of the rest.
Z had too much build up and filler moments and was too serious almost all of the time.
Dragon ball was more of an adventure/comedy then an action show.
Super is serious at times but knows how to be light-hearted. Super is also a decent pace (we don't want multiple episodes filled with redundant fight/dialogue scenes to have the plot line moved; every episode feels important). Honestly, if nostalgia weren't in the way, I'd probably view Super as the best dragon ball show period. I'm currently only on the black part of the show (I have always watched the English version and I refuse to start watching the Japanese version now, even if it is ahead by a ton) so please don't spoil anything, but as of this point in the show that is how I feel (and I feel like the show is improving drastically as it goes along).