Which do you prefer Window Units or Central Ac for rentals?

[Shane Craig]

To give you some back ground information all of my units are 2bdrm/1ba and are about 900 sq ft. 

I prefer window units over central ac units because of the cost( you can purchase a 17000 btu unit heating and cooling for $1000) and less issues on repairs. Also in my experience I don't receive more rent for properties that have central air. 

What do you prefer and why?