I think much comes down to what's practical and whats affordable. I can buy a FX5 for 200 if I look 230+ everyday, it does a great job, no arguing there. I can buy 2 Aquatop500s for 130 each and its a great running filter, I own 2 400s without a hitch in 2 years. Or you can buy one of the larger Ehiems for what 390 to 500 give or take I haven't researched it. Now looking at that why would I buy one of the upper end Ehiems in a higher price range for the unit and parts when needed, when I can buy 2 FX5s and maybe 4 or 5 Aquatops? Sure some do better than others, one does mechanical filtration better, the other does bio better. Fact is it comes down to what works and they all do. Volume, bioload GPH who cares really when you can mix or match what you want, to do what you want, for a price you want. I think much of the hype for the FX5 is the shear number of people that own them and love them. Sure some have problems but find me a filter that doesn't? I love Ehiems, I have had 2 smaller ones. but to me for a filter they are to expensive, sure they are nice run great and have a huge following as well, specially Europe folks. But for a canister filter they are too expensive. No it's not about money but practicallity and what works for the user, no right no wrong!