Opening gates to fight - which hero to use?

Ok, gurus. When you open your gates to fight, which hero should one use? (I gather you make them the mayor)

The defence hero with high intell or

the hero with the highest attack stat.

I know it's good to keep your gates closed if possible, but when the situation occurs, I just would like to know which to appoint as my mayor for the attack.

cheers

Your mayor wont fight. The best attacker will be chosen automaticly from the idle heroes.