Which is better, Kilz or Zinsser?

Which is better, Kilz or Zinsser? Which is better, Kilz or Zinsser, depends on job and personal preference, both are reputable primer brands with strengths. Kilz Original oil-based is strong for heavy stains and odors, comparable to Zinsser Cover Stain oil-based, both good, some pros prefer Cover Stain for adhesion on glossy surfaces. For water-based all-purpose, Zinsser Bulls Eye 1-2-3 is often rated slightly better than Kilz 2 for adhesion on slick surfaces, stain blocking, and versatility, with good low odor, though Kilz 2 is cheaper and widely available at Home Depot. For severe smoke, fire, and pet odor, Zinsser B-I-N shellac-based primer is considered better than any Kilz product, as shellac seals odors most completely and dries fastest, though more expensive and strong alcohol odor during application. So for general DIY, both Kilz and Zinsser 1-2-3 are good, Zinsser often gets edge for adhesion, while Kilz Original is strong budget oil option. For worst stains, Zinsser B-I-N shellac is generally considered best overall, better than Kilz. So better depends on stain severity, surface, and odor, with Zinsser shellac top for heavy-duty, Zinsser 1-2-3 slightly better water-based, Kilz good value.