All fish are individuals so remember what all these folks are saying is more about a trend rather than a rule. Having said that:
I have never seen a JD dominate a GT. GTs tend to be more offensive while JDs tend to be more defensive.
Beauty-wise, its in the eye of the beholder. I mean, which is better looking? An apple or an orange? Same difference with GTs and JDs.
Both can be curious.
Both can be timid.
Both are easy to care for.
Both grow real slow. I *think* JDs will eventually get bigger than a GT but it takes a long long time for that.
I personally prefer GT but I own both.