Sump.
One of the basic ideas of the sump is just that it adds overall volume to tank...creates more balance, gives fuge room etc. The only way I can really not imagine a sump is if it were like a ten gallon or smaller and you do the aquaclear filter fuge mod, but then again that kinda is a sump in itself.
also I would not use a canister, it is a nitrate factory. My 90 reef has been set up for around 8 years I think, I have a 35 gallon sump with a skimmer, a divider for some LR that I did not use and some carbon socks. I just manual dose also. It sounds like the sump creates more work, but at the end of the day it is very convenient.