Most people who repair their own vehicles are aware that there are many brands of tools on the market. Especially when we are talking about the basic wrenches, sockets, ratchets, and screwdrivers. Ask 20 people and you will get 20 opinions. There are, of course, some commonly held beliefs and some basic truths. No matter who makes the tool, a proper fit in your hand and on the fastener, will make for a better experience and better result. More expensive doesn't always mean better tools, and crappy tools will always produce crappy results.
Hand tools generally fall into one of three categories. Premium tools, good tools, and tools you loan out and don't care if they come back. Many of us have some tools in the last category and when they disappear we use that as an excuse to buy a tool from one of the other categories. So for the purpose of this discussion we will concentrate on the first two categories.
Premium tools cost what they do for three reasons. They fit the fastener properly. Nothing else in tool use will pay the dividends that this does. Proper fastener fit, means that the tool will not be rounding off fasteners or slipping off and causing busted and bloody knuckles. The second reason that premium tools are expensive is their construction. They are made to very tight tolerances, made of excellent quality steel, and are made with comfort in mind. These three things allow you to place a lot of torque on them without them flexing, and in comfort. Operation remains smooth. The third reason is warranty. All premium tools carry lifetime warranties but you are not likely to ever need it unless you use the tool so much it wears out. Breaking premium tools when used in the manner they were designed for is almost unheard of. And when you need a new one, you can usually get them mail order or off the vendor truck in short order.
Good tools share many of the characteristics of premium tools but generally are not made of such high quality steel. The DIY guy at home usually won't notice the difference except on rare occasion. Many strides have been made in recent years in tool making to allow mid priced tools to compete with premium tools for nonprofessional use. These tools may not offer as snug a fit as premium or the fit may not be as consistent throughout the set as premium tools. The shape profiles may not be as good so they may not be as comfortable in the hand. They may flex more under heavy use since the steel is not as good, but most DIY guys won't notice anyway. In many cases, good tools also carry lifetime warranties, but you'll have to go get the new one as no one is going to bring it to you.