I suggest the Rena Filstar canister filters. They are relatively cheap compared to some other canister filters. They work great and they are what I have used when I need canister filters. As with any canister filters they do need to be cleaned often depending on the system.
The highest rated salt water aquarium canister filter is A Aquarium Pharmaceuticals RENA FilStar xP3 canister filter. They can be pruchased for under $200. 00. One year Manufacturer`s Warranty. For aquariums up to 175 gal and has a flow rate of 350gph