I do like both of the dragons, but I have to say Reshi is my favourite. Although Meyneth does bring up a very interesting point, I feel the devs were going for a "passion vs. thought" type of dynamic (similar to Valour and Mystic). Both are important in my books.
In the end, my choice came down to design, and I prefer the more graceful, cloudy aesthetic Reshi had going on. The only thing I don't like about it is that poorly placed tuff of fur, but it's not enough to ruin the dragon/fire type's overall look in the end.