Dottie:

To be perfectly honest, I would be inclined to go with the painter that intends to use SW Duration paint. This paint is widely regarded to be Sherwin William's best exterior latex paint, and Sherwin Williams generally makes good quality paints.

Consumer Reports NEVER EVER said that Behr was the best paint. They gave it a "Best Buy" Rating because it's better quality than you'd expect to get in a paint costing $18 per gallon. That's only because when a hardware store chain decides to start selling their own house brand of paint, they do surveys to find out what their customers needs are, and what their customers feel decent quality paint should cost. The hardware store chain then gets estimates from several different paint manufacturers to supply it with paint costing from $25 to $40 per gallon (for example) at a rate of 5,000 gallons per month (for example). Each paint manufacturer sharpens up his pencil and figures out what he can do, and since the price has already been determined, the volume discount the hardware store chain would normally get ends up going to the consumer in the form of better paint for the price they're paying.

The above is the ONLY reason why house brand paints like Home Depot's Behr brand or Lowe's "American Tradition" paints often score "Best Buy" ratings in Consumer Reports. But, since your average consumer knows next to nothing about paint, they read more into that Best Buy rating than they should, and conclude that it's the best paint available, and that's nonsense.

What I'd do if I were you Dottie is to phone around to several other painting contractors you haven't dealt with yet and just tell them you have to choose between Sherwin Williams Duration paint and Behr Premium Plus or Behr Marquee. Ask them which paint they would choose if they were painting their own house. Discourage them if they start fishing for information, such as where you live and whether you want a free quote from them as well. Just tell them you want to know which paint they'd use on their own house if given the selection you have to choose from.