For my 75gal tank I have a Fluval 404 and a Penguin 330. I'm quite happy with that combination. The Fluval cannister is great for its versatility as far as the media combinations you can put together, but also having a HOB
like the Penguin makes it very convenient when I want to do a quick change of something, like Peat granules for instance. I like the Bio-Wheel feature of the Penguin as well.
I chose the Penguin over the Emperor because it's a little slimer, allowing me to get the tank a little closer to the wall.