If I had to choose one? It would be a Wet/Dry. To me it is superior in biological. Canisters to me are the best physical filter. HOB filters are decent at both. There is not one "best" filter. Although I think my Wet/Dry actually does do a pret6ty good job at physical filtering. A lot better than I thought 
Of course now that I think about it with the FX-5 for example does give you the option of physical, biological, and filter media (example- ammonia chips, chemi-pure, ect.) You can do that with the others but usually you have to prefab something yourself. A lot of the canisters are drop and go. If I was to run a 55 I like my emp. 400s, anything up to and including a 125 I like the FX-5 (although a 125 greatly benifits from a wet/dry), and anything above should be a wet/dry canister combo or a wet/dry imo.
Of course now that I think about it with the FX-5 for example does give you the option of physical, biological, and filter media (example- ammonia chips, chemi-pure, ect.) You can do that with the others but usually you have to prefab something yourself. A lot of the canisters are drop and go. If I was to run a 55 I like my emp. 400s, anything up to and including a 125 I like the FX-5 (although a 125 greatly benifits from a wet/dry), and anything above should be a wet/dry canister combo or a wet/dry imo.
