I only recommend Raritan's "CP." The primary reason is that Raritan doesn't retain a staff chemist, and we simply cannot keep up on all the toilet and tank treatments, and "smell good" products that are out there - many of which don't even list their ingredients on their packaging.
The retail price for a 22 oz. bottle of CP is $12.99. If you call Mike at BoatFix, (603) 856-8841, ext. 252, he'll quote you a better price for it. BoatFix no longer lists it, by itself, on their site, but they can still supply it.
BoatFix also carries Raritan's "Potty Pack" (a 22 oz. bottle of CP plus a 22 oz. bottle of KO) for $18.04, where Raritan's retail price is $25.46, so it's roughly a 30% discount from retail. (I'd expect a similar discount on CP, by itself - part # 1PCP22, in a 22 oz. bottle. It isn't offered in any other size.) For those of you who are in the dark, "CP - Cleans Potties" is a toilet bowl cleaner; "KO - Kills Odor" is a holding tank additive.
Whatever you choose to use, be sure to read the label on the product and avoid products that contain chlorine, petroleum, kerosene (such as pine oil), and if your toilet has plastic parts especially avoid ANY product that contains phosphoric acid in ANY quantity - it attacks some of the commonly-used plastics that are used in marine toilets and causes them to become brittle and crack. Dow's bathroom cleaner (Scrubbing Bubbles) is one of those which contains phosphoric acid.
Products that are used in the bathroom at home usually aren't suitable for use with a marine sanitation system: toilet, holding tank or treatment system.