me, i got one exhaust fan, 1 new psu fan, and a 90mm fan i just put in my plexi on the side.
i would say that its better to be equal, just because if there is negative pressure in the case, it makes the exhaust fans work harder, and thus be louder, same concept with intake. if there is positive pressure in the case the intake fans will be loud. so i try to keep it equal or atleast tone down the exhaust fans and put my intake fan on max.
another thing: if you have say 3 exhaust fans and 1 intake, a fan filter will do nothing on the intake because air is going in other places, so if you have filters on your intake fans, its better to have more intake than exhaust because you dont have unfiltered air coming inside of the case.