Hyper Offense > Balanced
I think Hyper Offense would definitely be a much better choice for Mega Gallade than Balanced.
Mega Gallade excels in stats such as Attack and Speed, and has great defenses to go hand-in-hand with in. I don't really see the importance for him being a balanced fighter.
There are plenty of attacking moves to give this Pokemon, with great amounts of STAB as well.
I actually would've chosen him being a Balanced fighter if his stats were a little more compact (more average) rather them having him excel in some categories that give him potential to be a Hyper Offense fighter. For example, a great Balanced fighter would be more so of Mythical Pokemon like Arceus, Shaymin, or even Manaphy. Their stats has a lot to say about their choice of fighting - not only their moves.
Your Choice! Hope I helped! :)