My first reaction is "don't ask me, I get my paint free from the recycling center."

When I feel the need to buy paint I go to the reclaimed goods thrift store where they sell merchandise that has been water damaged, etc. They even custom mix the paints - and know what they are doing. They're amazing. When we wanted to paint the exterior of our house and, thus needed large quantities of the same color, we bought the paint at Wal-Mart which was highly rated in Consumer Reports.
But seriously, I've done a lot of painting in my time. #1 - If you like one of the Ralph Lauren colors just ask the store to tint your paint to that color. It doesn't have to be the Ralph Lauren paint. The dyes are all the same. #2 - My brother insisted on using Ralph Lauren paint when he remodeled his house. I didn't like it (yeah, my brother picked the colors; I did the painting.

) The first batch of paint was my brother's fault. He picked the wrong base - one that was too thing - and the guy at the store who did the tinting didn't double-check. Even with the second batch, though, the paint didn't quite flow right and it splattered a lot.
Now the paint I get at the recycling center tends to be contractor paints (not brands you'd find at the hardware store). Those are pretty agreeable to work with even with a brush and roller instead of a sprayer.
Anyway, the short answer is: the QUALITY of the paint means more than the brand name. You have to select the right kind of paint for your application.
For instance, if you're going to be painting in a deep, dark or difficult color (yellow and red) your base has to be suited to being mixed with all that dye (which thins the paint.) If you're painting an area that is going to get lots of wear, use a paint that is 'scrubbable' like a semi-gloss and do a couple of coats. Fix problems in the surface and prime it if it is fairly fresh and new. Tint your primer so it is a complimentary color to the finish paint but slightly different so you can see where you painted and where you still have to paint. I can't emphasize surface preparation enough.
As far as color, I had a girlfriend who agonized over which shade of the same color. I mean really, it took her forever to make a decision. But you know what? Paint looks different on the walls. It changes with the light in the room. The colors reflect off each other. (I once painted a bathroom with medium blue walls and a white ceiling and ended up with a baby blue ceiling because of the reflected light - I know how to fix that now by painting the 'white' area a light yellow instead.) So now when I go get my free 'oops' paints, I pick out colors that are "close enough". No one is going to know I had hoped for a different shade anyway.