The 3 that I use and always have used, not only in the tractors but my big truck with it's 3406 Cat as well. Today, a certified by the EPA biocide is almost mandatory and far as I can tell, Bio-Kleen is the only EPA certified biocide on the market. Easy to tell as well. Just look at any bottle of diesel additive that touts itself as a biocide and see if there is an MSDS cautionary label attached 'as required by Federal Law'. No label means no biocide added. Real simple actually and you don't ever want to get microbial growth in your diesel as it's very expensive to remedy. I know, been down that road in the past and it wasn't a cheap date so buy the biocide and use it with every tank of fuel. I keep more than one bottle of it on hand all the time and the dosage per gallon of diesel is small so a bottle goes a long way.
When it comes to microbe prevention, an ounce of prevention is worth a pound of cure.