Sumps are usually cheaper, and very useful on larger systems, but canister's, if you can afford them, are definitely worth the investment. Not have to clean the filter but every 6 months can be nice sometimes...
Got a pic of the tank and stand here ... as you can see its drilled for direct attachment of canister filters along the rear no hoses or pipes required and no priming needed.
A closed loop would be something like running a line to an external pump, then running several Nu-clear canisters or similar, then running back to the tank.