I know both of them are 2 of my favorite characters in gaming,anime,manga & Final Fantasy this is 1 of the rounds I've thought of to have fun with comparing different characters & of course to share our thoughts enjoy.
As for me it's kinda hard to tell because they both can be a little sneaky if i had to pick one sorry Yuffie I'll admit you're pretty good especially the way you sneakily steal our materias but i have to give the win to Rikku because since she can steal but however she can also mix items & maybe make items even more powerful.
Now it's your turn to share be honest with all of us,have fun & remember this question is only for fun enjoy 🙂.