Big Mac Sauce. Basically created a $150B empire so both objectively and subjectively it is at the top. McDonald's would be Burger King today if it used mayo instead (lol).
Heinz Ketchup. Classic for a reason and somehow still difficult to copy perfectly. Hence why no-name white label ketchup is trash and makes you feel extra poor for cheaping out the extra $1 for Heinz. You only make that mistake once.
Renee's Mighty Caesar salad dressing. They actually perfected one of the most internationally ubiquitous salads out there. I'm surprise Kraft hasn't destroyed this brand yet but somehow the recipe remains unchanged.
Honourable mentions:
Swiss Chalet sauce. Pride of Canada. A great sauce but just too inconsistent from location to location. But when it's made right, it's so damn good.
Chick-fil-a namesake sauce is top-tier but just not 10/10. Maybe a 9/10.
Sweet Baby Ray's is arguably the only mass-produced "actually good" BBQ sauce out there so that's worth something.
Arby's sauce is a bit sweet but still a good sauce. And really unique. Shame they gave up on Canada. Really hard to find them these days as they are relegated to legacy shithole locations.
Balsamic vinegar - dunno if it counts as a sauce. Fair warning: there is such an extreme discrepancy between brands and countries and vintages. Legit Modena aged (15+ year) balsamic vinegar is 10/10. But your average grocery store brand is basically darkened white vinegar... Blasphemous.
Buffalo wing sauce, but again, just way too inconsistent. I'm talking a legit Buffalo Butter sauce. Unnaturally orange and almost "creamy" in a weird way. Those can be god-tier when you find the right wing joint.