Ive had several penguins, I would take a penguin over an aquaclear anyday. If you dont wanna spend the money on the cartridges you can either get the aquaclear cartridges from walmart, or order the bio3 penguin clamshell cartridges from drsfosterandsmith. The clamshells are like 99 cents a pop. Once you have the clamshells you can just cut filter floss or bonded pad, and clip a new piece in whenever it wears out.
The aquaclears hod a crap ton of media and are easier to modify. In my ac110 I can fit 1/2 litre biomax, 3/4 litre seachem denitrate, an ounce or so of carbon, and the 110 sponge.