Neither is useful as disease control in a single tank set up. Simply put, any pathogens can and will readily exist in a tank without ever passing through your UV or Ozone reactor. They can be useful in a multiple tank central systems to prevent spread of disease from one tank to another, but will not have any effect on disease within a given tank should some disease organism be introduced.
That said, Ozone can be beneficial to overall water quality and is quite useful in that regard
