What is the best method of cleaning the PS4? Compressed air, vacuum?
I would be very careful using a vac near your PS3, PS4, PC or any other electronics because it can really mess things up. I have seen power supplies go instantly dead from the static electricity. I would suggest you use one of those very soft disposable dusters and nothing else. Also you can use certain kinds of compressed air just be careful
A vacuum hose attachment is what Sony themselves suggested for cleaning the air ports on the PS3. I think as long as you're grounded you're not going to cause any damage to the power supply.
I absolutely would not suggest using compressed air, as it's only likely to push dust further into the system.