Shooting lasers out of your eyes is like looking really hard until energy shoots out.
Lasers from your mouth is like yelling/roaring so hard a concentrated beam of light shoots out. In my opinion that's more satisfying, yelling at people while also hitting them with a laser.
"{lasers}WHY DID YOU EAT MY LAST STICK OF GUM!?{lasers}"
Also, your mouth is bigger than your pupils so you would have a larger and therefore more powerful laser.
That said, aiming with your mouth would be harder, while it would be easier with eye lasers because your eye lasers shoot exactly where you look so you wouldn't have to adjust or anything.
You know, I should have put in finger lasers as well...