I have had a Marineland HOB filter, and Aqueon HOB and many of the sponge filters with the pump. The sponge/pump idea I like but... they are loud. The pump itself does the buzzing noise and the bubbles from the sponge are loud. The Aqueon hang on back is quiet but... I am not a fan of the big clunky looking filter on the tank.
I have never used a canaster filter mainly becuase the ones they sold at Petsmart didn't fit under my stand. I don't want a filter sitting next to the tank. It just looks yucky in my opinion. I prefer to have it hidden. Another reason I use the sponge is that I can plant all around it and you don't even notice it there (other then the bubbles)
Which filter systems have you guys found to be the quietest and also very effective?