Ehhh - skilter.
I had one for quite a while, and while it did pull out some nice skimmate (with a slight mod), I hated having to replace the air stone to keep it running efficient. The skilter as-is with the venturi adds bazillions of micro bubbles into the tank. The mod that I did involves an external air pump and a wooden air stone. Using that mod it made pretty good skimmate, but I had to replace the air stone usually every couple weeks. Kind of a pain.
I have heard great stuff about the bak pak R - the one without the bio-bale.