After 3 1/2 years full timing I have probably tried all options. I have settled on using nothing during the bulk of the year except lots of water when on full hookups and still nothing when boondocking just a little less water. During the heat of the summer when I'm on my host site I have to dump my black tank about every two weeks and in August I will start to get a small bit of order between dumps. When this happens I add just a little of the dark blue stuff. Brand doesn't matter, what ever is cheapest at the time.
Basically I don't use anything on a regular basis, just when in really hot weather and only then when I have a bit of odor.
2006 GMC 2500HD CCSB 4x4 Duramax/Allison, Titan 52 gallon fuel tank, Prodigy Controller, B&W Companion Hitch
2010 Jayco Designer 35RLTS, Cummins/Onan RV QG 5500 EVAP, Progressive Industries EMS-PT50C, TST Systems 507 TPMS, RV Flex Armor Roof