The best drainage option depends upon the user’s need. Whatever is convenient to them is the best way. If you don’t have to move the dehumidifier, you should choose the direct drainage option to keep the operation running without any effort.  If you intend to move the unit, then you should choose the manual one. Although you have to empty the bucket, it is easy as the units have an automatic shut-off. They can be worry-free and do it when they get the opportunity to do so.