Rena and Magnum only tow of the 4 big brands I have not had issues with. Fluvals are prone to leaking problems on many setups(very sensitive to head hight) and Eheim are very expensive, and parts are sometime cheap quality such as the intakes and out takes the filter it self is very good though.
My cascade 1000 is about 2 years old. The pros to the cascades are: they're cheap, they're quiet, they're easy to prime, they're great. The cons: you can crack the fittings if you overtighten and there is a little bypass. I run filter floss in the top tray and i'll see a couple big turds on top of it when I clean the filter. About 3 times a year.
I have 2 Rena XP3's, an XP4 and a Fluval 405. The Fluval leaked, was hard to prime and I hated the way it connected to the tank with the corrugated hose (seemed like it would fall off if a fish bumped it). It is sitting under the cabinet as a spare for emergencies (if all of my other filters die at the same time). The Rena's have worked well for over a year (the XP# better than the XP4).
I haven't tried the FX5 but I am tempted to considering all of the positive feedback it has received. It's just hard to overcome my bad experience with the 405.
The Eheims seem nice but are pretty expensive. I think I'll probably stick with the Rena filters as they are working for me. A sump is still a better way to go as you can have a much larger volume for media and never have to worry about priming! I use both as it is good to have redundancy with your filters (don't rely on just one in case it fails).
^ The Fx5 is a much higher quality than the 04 or 05 series filters. I was very pleased. The function of the baskets annoyed me which is why I had to modify the filter but it worked great before and after and still does.
How did you modify the filter? It looks like it would be good for mechanical filtration with that big foam block around the baskets. I'm thinking about getting one for my 270 to go along with a DIY wet/dry filter made from a rubber maid trash can.
I had an Eheim and was not impressed with the flow rate. I now have a Cascade on my Feeder QT tank and I'm much more impressed with it than the Eheim. But my Fx5 rocks! So based on that I voted for the Fluval.