Depends upon how much you want to spend. As a spare does insurance cover it? Then I'd go for the mobileaire. Out of pocket -- I bought our pari proneb ultra brand new for less than $50 and the devilbiss pulmoaide for about $100. Still covered under warranty. We use the pari more for traveling since it's compact. The devilbiss is our everyday one. We also have a devilbiss circa 1992 from DH's cousin whose daughter had asthma and it still works like a charm.