I use both and I like the HOB's better.
The reason being is that I'm always concerned that one day the lids on the Canisters may leak. I think the canisters can do a better job filtering the tank, but HOB's are easier to maintain and get in and out of IMHO. Your choices for filter media are endless in a canister filter. Ultimately I am going to go with pot scrubbers and a nice layer of reusable filter floss.
The reason being is that I'm always concerned that one day the lids on the Canisters may leak. I think the canisters can do a better job filtering the tank, but HOB's are easier to maintain and get in and out of IMHO. Your choices for filter media are endless in a canister filter. Ultimately I am going to go with pot scrubbers and a nice layer of reusable filter floss.