Canisters build up detritus in their substrates over time without proper/regular maintenance. Over time, without proper cleaning, they house and produce nitrates when the filters should be removing it.
A sump on the other hand, isn't really a filter....just added space/volume to house other filters (a skimmer, more LR
Personally, a sump with a few compartments to house LR
rubble, and another for a skimmer is hard to beat. They're much less maintenance than a canister filter imo