Eheim Classic Canister Filters
Well there just simply isn't a better filter on the market. With the intake on the bottom and the exhaust on the top, there is simply no place for water to bypass the media and hence the filtration is far more efficient. I hear people talking about the difficulty in cleaning filters but most of them seem to do it far more often than is necessary.
One of my tanks is a heavily planted, heavily stocked community tank with an EHEIM 2213 on it. This filter has been running for me now for just under 10 years and I have never had a failure yet. As far as cleaning goes, once every six months is the most I have done it but currently this filter has been running for eight months since the last time I have opened it up. Since there is no bypass, you know from the flow rate wether or not the media is plugged, and you can also see into the canister to see if the media is plugged.
Fluvals, well at least the old style were not too bad but there was quite a bit of media bypass, still they worked quite well...the new Fluvals don't even come close. Any one who has one try this little experiment....open it up, take the lid off of the last filter media tray, place a piece of plastic wrap over the tray and reinstall the lid...reassemble the filter and fire it up...you will be very surprised by how much water still runs through this piece of "equipment". Once you see this you will run right out and buy an Eheim..they seem more expensive than Fluvals but in the long run, they are actually cheaper as they don't break down, the media is almost infinitely reusable and they are extremely efficient...remember folks Gunther Eheim invented the canister filter.
Try to get the classic style though, as they are the least expensive and ultimately the most efficient. You can actually trust their tank size ratings.