I Have both AC and penguin bio wheel.
to be honest..I prefer the AC over the penguin
the ac's are easier to maintain, I use 2 sponges in each and the biomedia(weird they call it that cause the sponges hold bacteria too)
the cartridges on the penguins IME clog up fast and will affect the flow to the biowheel(also snail get caught in the biowheels keeping them from spinning..you need to check the penguins more frequently.
the ac, I rinse the bottom sponge once every two weeks and then rotate the sponges..with the sponge a squeeze or two in old tank water and you are back in buisiness.
that said...they are both good filters..the bio wheels have more surface area ..the bacteria only need to reamin wet and fed to survive..the rotaing(slowly) wheel does this efficiently..with all the pleats you have a bunch of surface area.
the ac's use a basket with media water flows from the pump to the media basket up thru the media and out to the tank. the big plus on these is their ease of maintenance and the ability to change media. you can run sponge, carbonh, biomedia or any numberof other media(phosphate removers etc)
so take your pick.