Steven.
Wallace is fun in his own way, he's artsy and glamorous. But Steven is the character that had the most thought put into it and develops a real friendship with the player. This alone makes me prefer Steven, especially in Oras. He is so involved in gen 6 from giving you the eon flute to going through the delta episode by your side.
Also Steven is always introduced at a higher difficultly level than Wallace. In Ruby and Sapphire he is the league champion, and Wallace is a gym leader. In Emerald Wallace rises in the ranks with help of Steven, but Steven is still clearly the final boss with Pokemon more than 20 levels higher than Wallace, closer to Mt Silver Red.
EDIT: Sorry! You answered the question before me, I missed you. Let me answet YOUR question now 正真正銘
Deoxys defense. I like the speed form best of all, but between attack and defense I would pick defense because powerful as Attack form is it's more intimidating for me to use. It just takes one aqua jet to die.
Red as a character and trainer or Blue?