All paint sold in the the US is supposed to have a MSDS sheet available which lists many (but not all) of the major ingredients in the can.
The best pigment is titanium oxide (dioxide), but this ingredient is relatively expensive. Lower quality paints will add fillers like Kaoline ( a type of clay ) or even silica ( a form of sand). Kaoline is a good ‘hider” which makes the paint cover well, but it can give the paint a grey cast that makes bright colors impossible. Silica provides hide and makes the coating tough, but again gives the paint a grey cast.
The best paint resin for general use is Acrylic, but just because the can says 100% acrylic resin doesn’t mean that the manufacturer hasn’t added “extenders” like styrene or vinyl. Besides being cheaper, these additives can can shorten the life of the paint and cause unpredictable reactions with other products like primers or later coats of paint.
There are no secrets in paint. All the manufacturers know what every other maker puts in the can. All the major manufacturers make
great paint, not-so great paint, and everything in between. The major difference is how much is spent on advertising. If the money is spent on the tube, it’s not in the can.
Be wary of what you may find on the web, I constantly see comments from “pros” that are complete nonsense and appear to have been put there by friends of the manufacturer. Consumer reports has annual reviews of paint and is an objective reviewer, unfortunately the range of products tested is limited.
I personally use Glidden Fortis on the outside of my home, Ralph Lauren on the inside and Cetol on the doors. The painters are amazed at how long the paint lasts. Fortis is the top of the line made by Akzo Nobel, the world’s largest coatings manufacturer. Ralph has no clay in it and yields beautiful colors. I have tried many coatings on the mahogany doors over the years and Cetol is the best I have found yet.
A properly done paint job should last for many years. Skimping on the paint, the last and least expensive part of the project, will only hasten the day when it all needs to be done again.