The ones that give dresspheres are my favorite because I loved getting new dresspheres.

I want to play this game again now...

But purely for just the challenges, if you take out the dresspheres as a rewards? I really liked the investigation on the Mi'hen Highroad, and I like the Rikku result. I liked confronting Garek(?), even though the fight was hard on Mt. Gagazet, because it was touching.

I haaaaaaaaaaaaaaaate the Lake Macalania one where you do like 5 fights in a row. It's a shame you need to do it for the dressphere. I also disliked the Lightning Rod repair challenge.