maintainence via canister is definitely much much more troublesome as compared to sump.. a sump allows you to put filter media such as filter socks and you can have ample of space (subjected to planning of sump) to place your equiptments like skimmer, pumps, etc.. unless you really screw up your sump, it will never be a nitrate factory as compared to a canister..
IMHO.. Sump for the win!