Well How many oscar do you plan on keeping in this tank? If you are going to get 2, then you should really spend the money on a canister, get one that can turnover 400-500 gallons of water a hour. And I would also recomend using seachem matrix as your filter media. It does extremly well in canister filters. If your going with HOB filters then you should get somthing that can turn over 1000-1200 gallons of water a hour. That is a bit over the minimum recomended requirements, but when it comes to oscars there is no such thing as too much filtration. I like to go with mixing the 2, I would get a powerful canister, like a eheim 2028, and also get a HOB like a ac110. I think AquaClear filters are the best you can get as far as HOB are concerned.