For camera replacement apps there really just is camera pro and camera QT from the same guy, QT looks better but PRO is faster and better apparently.
Although having purchased camera PRO IMO it's not ready to be a replacement for the stock one. It freezes, it's slow, the interface is ugly, it doesn't work always as you would expect. Sometimes the focus doesn't work, it's pain when trying to take a quick pic to notice the phone isn't focusing. It takes a few to many clicks to get video going.