Once youve owned a decent filter like an FX5 or some of the ehiems, you see the flaws in the aquaones - but you get what you pay for i suppose. Just the build quality - down to things like the taps, connectors etc.., to the media, hosing, and they arent as energy efficient also.
Flowrate isnt everything like a lot of people believe. I use my eheim purely as a bio filter, where a lower flow rate is much better, plus takes 5 minutes to clean, has good media, uses a mere 8w of power, and is going to run and run and run.