you surely want a 2stage comp. if given a choice. The cfm output on a 2stage is higher and the pressure cut-out is higher. With a 2stage I would get a 5hp with an 80gal tank, that way you have the reserve air needed for working tools. the cycle time will be less also. Make sure your electric can handle the load. If you can swing it I would look into an aftercooler with a fan also, that mounts between your units head and the tank and acts like a cars radiator, it cools the air going into the tank to room temp and the moisture in the compressed air will condence and fall to the bottom of your tank keeping it from being suspended in the air. The compressed air tube going into the tank can reach 300deg when run hard and will burn you fast with the aftercooler just warm.