For a 70 gallon I would go with two Marineland Emperors for 800 gph in flow. You want 10x or better the water collumn in flow. These are very good filters. The clam shells can be filled with bio ceramics.
I have an aquaclear 110 on my 75. They certainly aren't the cheapest but mines over 15 years old and still works great.
I recommend canisters on anything larger than 55 gallons, but the Fluval C4 HOB is about as close as you can get.
I'd definetly recomed the aqueon quite flow series...now I always use them in combination with a fluval canister filter....the fluval houses my bio filtration and I use the aqueons....two 75s on my 150 and 1 75 on a 75 gallon and 55 gallon....for my carbon filtration and water polishing....they are cheap and they run great