Exterior Paint on New Stucco
Second, the preparations and application will be more imporatnt than the actual paint they use. In dusty Tucson, if they don't clean the surface before applying the new coat, then any paint will fall off. If they don't cut the edges cleanly, then any paint will look messy. If they glop on the paint quickly instead of carefully smooth it on uniformly, then any paint will look clumpy. You are not just paying for a product, but also a service, and the service can determine the quality of the end result more than the product.
Moreover, you can instruct a good painter using cheap paint to change his product and still get a good job. You can't get a bad painter with a good paint to improve his lousy painting. Check out their references and take a drive to look at other houses they have done to get the best measure of which one you want to select. Look at the cleanliness of the corners, the transitions, and the trim, as well as the uniformity of the application. That is the best way to shop.
If you get the premium line of paint from any of thoes companies it will do fine, but to be sure it is the right product for your house just call the technical line ask them.
Painters use different brands for diffeent reasons and it could be the service they get or they like how the paint works or they feel that it holds up better than other brands.
Good luck on your paint job.