Another thing to keep in mind is that like all things, there are different grades of each type of valve. Unfortunately, the box stores typically only sell on price, and not quality. We have seen a great deal of defects and leaks with “economy” grade valves. A reputable plumber will always supply you with a better valve, and will also be able to install the best valve for you upon request. It is advised that if you are in an area requiring a gate valve, a good quality gate valve is a very worthwhile investment.
It always seems a little backwards to me that most people will put much more money into the label on their clothes, than the label on their plumbing fixtures and materials. Hey, you might as well look good while fixing that leak!