I have a part time home repair business and I regularly use them all.
If a customer wants SW, Bher, Valspar, or anything else, I do not talk them out of it. That way they can't come back at me, if they are not happy.
Here is my list:
Valspar- Is junk. Semi gloss is very slow drying, and shrinks up a lot. I would only chose to use this stuff, if it was a two story foyer, and it was hot weather. Then, the slow drying would actually be helpful, in keeping a wet edge. In cold weather, it takes forever to harden.
Bher- Decent. I usually don't buy it myself, but I don't mind using it. Some colors do not cover well.
Sherwin Williams- I use a lot of "Duration" interior, and "Resilience" exterior. Hard to beat for the money.
Benjamin Moore- You have never painted, if you haven't used "Aura", it's $70 a gallon, (for the interior, retail price). (I have never used the exterior). You can cover any color, in one coat. No priming, just one coat. I recently painted beige, over a dark Merlot wine color, in ONE coat. (See photo below). Making it cheaper than two gallons of Bher's best paint, and Aura is by far a better coating. You have to know how to put paint on heavy to do that in one coat, but it is possible with this product. Aura hardens much faster than the others, so it can be cleaned without damage, weeks sooner. Though I don't always buy it for my own stuff, I would use nothing else if I had my way. Any customer I have ever used this paint for, has loved it.
Sherwin Williams came out with "Emerald" to compete with "Aura". It's not even close to being as good.
Don't use Kilz water based primer for stains. Only the oil based product gives reliable results. You can buy spray cans, for this, if you have small spots to prime.
