which is better?

Air compressors come in a variety of sizes, styles, and weights, but in practice, the only real options are to use an oil-lubricated compressor or choose an oil-free design.

When it comes to oil or oil-free air compressors, oil-free air compressors are better for DIY projects, but both styles have their applications.

Oil Air Compressors - oil-lubricated air compressors are durable for heavy-duty use. These compressors are effectively silent, making them great for quiet neighborhoods. 

You must know that the oil used in oil-lubricated compressors is not motor oil. It is a special detergent-free, synthetic blend explicitly made for the ball bearings inside the compressor. 

Oil-free air compressors are lubricated. The Teflon-based lubricant was applied during the manufacturing process. These air compressors are mostly maintenance-free as well.