My dad was in the paint business his whole career (40+ years). We always trusted his painting advice until one day we realized "the best paint" was whatever company he was working for at that particular time. Changed 4-5 times over MY lifetime...
One thing I do believe, though, is what he said about all paint being made by the same manufacturer. When companies like Behr, Dutch Boy, Sherwin-Williams, etc., buy it, they add their own tints and all that stuff--I suppose some probably even thin theirs down. (Shampoo is produced the same way.) That's why everyone here has different preferences, and what some people love, others hate. There are too many "ifs" (wall surface, tools, temperature/climate, etc.) in every project to make one brand of paint always do the perfect job.
Here are a few tips I've learned over the years:
**Primer is fabulous. It can be a bit of a pain, because you're pretty much painting TWICE, but it makes such a nice surface for your paint to adhere to. I usually get tinted primer if I can--in fact, you really NEED it tinted if you're painting red or a dark color--and then use it as sort of a "test" to see if I'm going to like the finished color.
**Prices for a gallon of paint don't vary all that much. Spring for another couple dollars if it means you get a better quality paint.
**Don't assume that the advice you get from a paint counter person means that they really know what they're talking about. It's sad but true; just because they know how to run the tinting machines doesn't mean they know how to paint. Same with the advice you're getting on these boards... read the posts and then go with your best judgment.
**Get good painting gear. Don't buy the cheapest rollers. All-in-one kits are not always good quality, so not usually worth the $$ saved. Get good brushes (Dad always preferred Purdy). Don't go for the gadgety gimmicky tools, as they rarely do as good a job as using the basic tools.
**If you prime over spackle, you won't have dull spackle spots when your paint has dried.
**If you'll be working on several projects, invest in a good canvas dropcloth. I asked Dad for one a few years ago and I swear, it's the best birthday gift he ever gave me! It's sooooo much better than those thin plastic dropcloths, and it'll last forever. Also, every time I use it--and I use it often!--I open it up and it tells a story about our house. My kids love to quiz me on what color splatters are from what rooms.
**Buy one good sturdy paint roller tray and use it with disposable plastic liners. When your project's done, you won't have to wash anything out except your brushes (and your rollers, unless you toss them--I always do).
**If you need to stop painting for more than an hour or so, put a wet paper towel on top of the paint in your paint tray and then you won't end up with that pudding-skin goop when you start up again. This even works overnight!
**Poor paint coverage is not necessarily because of poor quality paint. Too often we try to get every last drop of paint off the roller, pushing harder and harder until almost nothing ends up on the wall. Instead, make sure your roller always has plenty of paint and you'll have good coverage.
There. More than you asked or ever thought you'd want to know about painting.
I LOVE to paint... wish you lived closer to me, and I'd come over and help!
--Jennifer
Paint's an odd thing---some people will swear by a brand while others hate it. 
