Do you want a quality job? It starts with quality products, One of those products is the contractor. Another product is timing. The easiest quality product to control is materials. Remember Quality plus service equals value. Your best value is through buying quality materials.
In considering your materials – the most expensive is usually the best value but not always. Some of the manufactures have gone beyond the call of duty to create products that are warranttied for the life of your home, at least until you move. So if you move every 5 or 10 years that warranty may not be necessary. A great exterior paint may not be so great if the painter tries to paint in full sun at 90 degrees. The surface may actually be over 100 degrees. No paint will dry correctly at 100 degrees no matter how much you pay.
All of the paint manufactures have great products. Most of them lead with a flag ship product that has provided them years of success along with some market differentiation by which support products can be included to provide you with the best package. Based on my field experience I will tend to use multiple manufactures on the same job – since I will try to pick the best from each manufacture.
The quality products will follow the quality applicators. So always ask what product is your favorite, or do you have a favorite manufacture. and ask why. The more information you can get the better. Some times just a quick phone call for confirmation is time well spent. If your contractor only uses one particular supplier take note – it may be because their business is totally dependent on leads from the paint store since their work does not speak for it self and create referrals.