It really is preference. I like DD just because the 10 on the bench actually doesn't really do harm, in fact, it helps. In S1 (Stage 1), you're playing Pokemon with 110 HP or less. I mean, EQing Yanmega isn't all that bad, but it stacks up after a while. And then you start to get sniped and can't do anything about it. With Donphan/Dragons you're running 6 Dragons come Kyurem's release. Getting sniped, which would almost never happen, is not a huge deal at all.
For Worlds, I actually think S1 will do better than DD because DD has no counter to Donphan, and it's a bigger issue than you think. But once Kyurem comes out, it'll be amazing.