The Fluval 104 worked well for my 10 gallon. It seemed to have the right amount of flow for the tank but it woudl have been powerful enough to use an inline reactor or heater if you wanted too.
The only flaw I have in the Fluval is the hoses. Fluval uses large diameter, stiff plastic hoses that are somewhat annoying to use. These hoses have a 5/8 ID meaning that the connections on the filter ar 5/8. To get around this annoying issue, I replaced the fluval hoses with standard vinyl tubing. I used a short piece attached tothe filter then a reducing 5/8"-1/2" plastic bard and ran 1/2 vinyl tubing to the aquarium itself.
Simple fix. Other than that the Fluvals are nice. Definately not as nice as Eheim, IMO, but good for smaller tanks.