Two of them are little and hardly filter and one is a homemade sponge 'n' pump filter. So really only one filter, the Aquaclear 50 HOB.
I just don't like filters. They use up power, look ugly, take up room, require cleaning (which I never do anyways), make noise, cost money and create a current. Apart from CO2 diffusers and water clarifiers, they're near pointless.