Kyurem just ruined it for the the Unova trio so sinnoh trio for me.
Then again, the sinnoh trio have the weirdest mouthparts and dialga has that thing he calls a head.
All of them have awesome typings.
The Unova legend story is completely dead while the sinnoh one is interesting.
Zekrom and reshiram are the best looking legendarys ever, while the sinnoh trio are quite cool.
Both origin forme of giratina and kyurem(not sure if it's his origin forme) are crappy looking legendaries.
Defenatliy the Sinnoh Trio. Dialga, Palkia and Giratina have more fun designs and better backstories than Reshiram, Zekrom and Kuyrem and two of the Sinnoh dragons are pretty girly looking. Enough with the many looking dragons already.
Plus, they have the most powerful dragon of them all, with the most powerful move, Dialga. And the cutest, Giratina's orgin forme. ~nya