Depends on your team I'd say. Explosive is better than Earth if you are running any kind of blitz sort of team. Thou in the case of blitz with WB asuma, Earth is better than Water--by the time your shield breaks down and they chipped into your life to make water matter, the match should be decided one way or the other. Ergo for those teams you should replace Water w/ Explosive.

Thou in reality, you don't get to be picky. I'd take a red wood over a purple or perhaps even gold water, for example.

And I'm using gale on my mei because her combo is REALLY good, so it actually makes some sense. Most ninjas thou, not worth the trouble.

And ice might be useful for your initiator or healer, it's worthless when it doesn't proc, but it is AMAZING when you shrug off a CC that would have cost you the fight. And in case of healers, usually sacrificing fire does not have a huge impact.

So there are some potential deviations, but generally speaking, the primary stats are the best.