If you could have any Kekkei Genkai except a dōjutsu which would you choose. Doesn't matter if it was filler or cannon.
I would choose Lava realease just because of it's versatility. Other than that explosion release could create mean taijutsu techniques
PS heres a link to the narutopedia of Kekkei Genkai if you want to see them all http://naruto.wikia.com/wiki/Kekkei_Genkai