There is no comparison in quality. BM will match any color you want

Color matching can sometimes be a problem when you are looking for a perfect match and are very picky about the color being exact. The problem isn't so much that Benjamin Moore can't match your color. They probably can. The problem is that most people choose a color from a color chip and then after they paint an entire room with that color, it doesn't end up looking like the color chip or it doesn't end up looking exactly like they expected. This could be because of lighting, shadows, sheen or the fact that painting a large area is always going to look different than a small sample chip. This is especially true with greens, yellows and light blues. You try to pick a squash like yellow and it ends up looking like the sun. You want a pale blue and it ends up looking like the sky. You want a sagey green and it ends up looking like mint ice cream. All of this has nothing to do with having your color matched in some other brand, but you may end up blaming your displeasure on a bad color match anyway, just because the color didn't come out looking like you expected. Also, it is important to realize that there is really no such thing as a perfect color match. All a paint store can do is get the color close enough to make most people happy. If you are not 'most people' and you are dead set in love with the color you have chosen, you should probably have it made in the brand that makes the color or you could be disappointed.

As for the quality of the brand Valspar vs Benjamin Moore, this really depends on what you are using the paint for. I have never used Valspar, but I'm going to assume that it's medium quality paint and that the durability of the paint isn't going to be as good as Benjamin Moore Aura. If the area you are painting is going to take a beating and you need a great durable paint that you can wash all the time, then Aura will probably be better. If not, then you probably won't notice much of a difference. I'm really learning these days as a painter that all of these 100 percent acrylic paint brands you can buy these days are pretty much the same animal as long as you choose top of the line. In other words, if you are spending $30 or more for a gallon of paint, I expect it to be pretty good stuff.

I know what you mean about blaming colour matching when the problem was really the colour choice. I had my house painted a paint colour-matched by BM. I hate the colour. At first, I thought that they got the match wrong (it was mildly off) but then a year later I realized that they were close enough it was not going to change the overall colour that match. I just made a bad colour choice that had green undertones (in a yellow colour).

I've tested the new colour options on boards and on large patches of wall - and I now realize that 2 colours that are marginally different do not change on the walls that much (so presumably the same holds for colour matched paint that is mildly not quite right). So I think that I will know that minor differences in a mismatch won't change much.

I would also supply the Benjamin Moore store not only with the Valspar paint chip but with a quart of the Valspar paint in the correct colour - as that way they can also compare the 2 actual paints (original Valspar and colour-matched BM paint) against the Valspar chip as the chips are on paper and the different sheen makes them reflect different.