noone - i reckon where I've got mine is your best bet. That way a bit of bent aluminium shrouding can duct directly to the front bar inlet. Also there is no other cooling or obstructions around there.
h2k - that's not so good as you've already passed air through the intercooler (slowing airflow, and heating the air), then partially through the oil cooler (remember air velocity is now reduced) and then through the radiator (if it goes through it at all).
remember what i said earlier that if you don't have exit vents, or enough airspace behind the cooler (be it intercooler, oil, or radiator) it will do NOTHING to cool the face of the cooler. Think of the practical example - if you open up the window of your room, and shut all other doors, there is fark all air flow as it doesn't have anywhere to exit. If you open the door the air will travel in the window and out the door, i.e. the path of least resistance. You MUST allow the air to escape once it has passed through the core.
hope that helps