IMO, the forced air s a bit better quality but is more high maintenance as mentioned above, it dries out the water faster so you have to constantly be adjusting the humidity, my region has high humidity and so dose my home, so the still air works just fine, but then as seasons change and the humidity is lower and you have to add more n more water the forced air comes in handy, also still air you only add water once again at lock down and leave it closed, vs forced air we know the fan dries up the water and changes humidity faster do you have to keep.adding water throughout lock down, now I.know I haven't pin pointed an actual.pro and con but I have pointed out the relative difference for preference depending on your climate region, and that is where one would decide over the actual pro n con.