i have two pen 350s on my 75 and i like them. they rarely act up but i will say that they do sometimes. i just ordered two ac70s off ebay to try on another tank because i like the fact that you can get parts and media almost anywhere and because a lot of people praise ac's on here so i figured i'd try them. as for your question i'd go with a canister, ime you can never go wrong with a nice canister.