My power plant has 8-10 rotary screw compressors. Two of them are oil free. Both types have lasted > 80,000 hours. Reliability is same or similar. The oil free initial cost was much much higher and the manufactures recommended preventative maintenance is a lot more extensive and costly. If possible, go with the oil lubricated and keep you outlet oil separator clean and working properly. Some copcompressershave them in the compressor and some are separate. make sure. Oil can carry over and damage down stream components like ddesiccantdryers.

Good Luck