It won't matter that much. Just choose what kind of character you want your avatar to be. A mage, a sword user, a speedy guy, the tank and choose according to which stats boost what, like magic for a mage, strength for sword user, speed for speedy guy or defense for tank.
I guess I'm having more trouble choosing a weakness, lol. I'm afraid choosing the wrong stat is going to really cripple me in the game or something.What stats to use as the strength and weakness is entirely dependant on what kind of character you want your avatar to be. He can do anything.