Which paint is better sherwin Williams or Benjamin Moore?

It depends who's buying...

Benjamin Moore's primary customers are the RESIDENTIAL DIY's. To these customers, the main criteria in defining a "good paint" is based on the ease of application (how forgiving is the paint) and scrubability (washable as it is most often referred as... although they are 2 separate things... see below).

Sherwin Williams's primary customers are the CONTRACTORS. To these customers, the main criteria in defining a "good paint" is based on the coverage qualities of the paint and bond (how well the paint sticks to the surface being painted - the substrate)

The following are some of only a few different qualities you can look for in paint. And just like almost every other product out there, none has it all. So it's important to know what your needs are and ask a painting professional (someone who is neutral) which one can best serve your needs.

Different qualities of paint:

1. Ease of application (the paint levels off easily to remove any roller marks or brush strokes)
2. Good Coverage (ability to cover in less coats)
3. Washability (the paint film repells the dirt from penetrating too deep making it possible to remove with water and a sponge)
4. Scrubability (ability to scrub the surface whether it's by rubbing against it or removing tougher stains)
5. Spread rate (ability to cover more area with less paint)
6. Bondability (ability to hold on to a substrate better)
7. Anti Mildew (ability to prevent to formation of mold)
8. etc...