From reading up on it quite a bit, people typically have more problems with the newer Fluval 04 series compared to
03. The 04 series did have multiple running changes made to the product as well, so it can be difficult to compare.
If you compare the build quality and fitment of Eheim and Filstar to others, the difference is noticable. Check out some reviews here:
http://www.cichlid-forum.com/reviews/category_display.php?CatID=104
Eheims have a 9.16 for the Pro II and 9.18 for the Classis, and the Filstar average out to 8.91. The Fluvals only have a 7.66 average rating. The Magnums only have a 7.16 as well. If you read through the reviews, you will get a good feel fot the issues people have had with Fluval and Magnum.
There will always be people that say, "I have had product X for Y years and never had an issue", the important thing is to compare the ammount of good, to the ammount of bad people say. Overall, there are VERY few complaints about Filstars and Eheims compared to Fluval. I would encourage anyone buying a canister to try to get their own hands on one first and see how it is made. I have a newly purchase HOT Magnum and the plastic molding on it is _junk_ and it would not stop leaking air no matter what I did. I gave up on it and bought something else.
Not all Eheims are that expensive, all three ECCOs are less then $100, and some of the Classics are under $100 as well. Filstars can be found for under $100 as well.
I would reccomend anything from Eheim or the Filstars to people buying a canister filter. Paying a little more can help save you from a lot of trouble later.