it's a matter of opinion. There's a matchup between the FX5 and a comparable eheim. It all just depends how much cost of running means to you (electricity), bio/mech filtration and the need of chemical filtration.
For a tank that big I think it would be wise to look at a mixture of things.
I have a BioForce 2000 Pressurized Pond (Canister) Filter powered by an (external) 1800 gph pump...
Mechanically speakling it would spank an FX5 and put it to bed without dinner...
I don't know it it's 'better' than others regarding bio-filtration but after several years of use it on a 300 gal tank and not once seeing any trace af ammonia, I'll argue that the other's aren't 'better' than my BioForce...