One reason I too would suggest the Aquaclear 70 (now being relabeled as a Fluval) is that it's so easy to avoid throwing away your beneficial bacteria.
The filters with cartridges that are floss and stuff bonded together fall apart in my experience. It takes some fiddling to come up with an alternative.
But the box on the Fluval/Aquaclear can hold "whatever", and the media is very long lasting - the sponge for mechanical filtration and the ceramic for biomedia.
There are good debates out there about carbon. My personal advice is to stash the carbon for another time if you need to medicate. In its place consider a piece cut from a canister filters water polishing pad, or other chemical filtration media if you think you need it. I've seen interesting suggestions for pumice and purigen. That's a whole different thread.
I forget if you have existing seeded media. A good start is the sponge on the bottom, your existing media in the middle, and the ceramic on top. Every so often shake the debris off the sponge and the ceramic rings. And after the sponge and ceramic are populated, you can fit the water polishing pad.
The C4 looks cool too. But my 29 does well, a touch overstocked, with a Aquaclear 50.
Sent from my iPhone with three hands tied behind my back.