A slow cooker promises to be a little fantasy grandmother who sits in the kitchen all day cooking for you, but use the wrong cooker and that dream could fizzle. A cooker might run hotter than expected, drying out the food or turning it mushy, or slower than you want, so dinner isn’t ready when you are. Then there can be issues with hot spots, which make food cook unevenly. And what if operating your machine is so confusing that you have to pore over the manual each time you use it?

For the ideal machine that would deliver a properly cooked meal and be absolutely simple and intuitive to use, we went shopping. Previous experience taught us that glass lids were a must, as they allow you to see progress without losing heat. So were oval-shaped crocks, as these can accommodate large roasts and offer more versatility than round crocks. We also wanted a generous 6- to 7-quart capacity. With these criteria in mind, we rounded up eight models priced from $39.99 to $148.71.

We tested these eight slow cookers, preparing a variety of recipes using both low and high temperature settings and varied cooking times. We used temperature probes to map heating patterns, and a panel of testers evaluated how easy the cookers were to use and clean. We also dismantled a set of the cookers to understand the placement and type of heating elements they contained. What were our favorites of the bunch?

The KitchenAid 6-Quart Slow Cooker With Solid Glass Lid ($99.99), our former winner, handled every recipe with perfect results, albeit a bit slowly. Its thick stoneware crock, insulated housing, built-in thermal sensor, and crystal-clear controls put a well-thought-out design at your service—and at a moderate price. The Cuisinart 6-Quart 3-in-1 Cook Central ($148.71) is also a solid choice. It offers the advantages of a light, unbreakable metal crock with stay-cool plastic handles, as well as a brown-and-sear function that lets you skip using a separate skillet before slow-cooking in recipes that call for it.

➜ View Slow Cooker Equipment Review

In addition to testing large slow cookers, we also tested smaller 4-quart slow cookers; they are handy for recipes scaled for two, though we found in our recipe testing that this size of slow cooker is quite versatile and can actually be used for many other recipes. 

➜ View Small Slow Cooker Equipment Review

It’s not uncommon, as you walk through the offices of America's Test Kitchen, to pass a table of 25 or so staffers silently concentrating on tasting a dozen varieties of olive oil, peanut butter, or soy sauce. If you continue to the main test kitchen, you might find, say, eight slow cookers, each hooked up to a separate thermometer, each of which is connected to a computer so we can gauge how evenly they maintain a temperature over time (pictured below). Walk out the back door and you might see someone dropping one portable grill after another onto the pavement from a specified height to see how well they will stand up to abuse.

It’s all in a day’s work for our Tastings and Testings team. And if you think the test cooks here at America’s Test Kitchen are obsessive in their quest for the best—and you’re quite right, they are—you should spend some time with this team. The lengths they go to in order to be sure that their tests are accurate, comprehensive, and conducted on a level playing field are enough to make the rest of us look relaxed.

There are strict written protocols for selecting the items to be tested, for running the tests themselves, and for evaluating them. There are detailed instructions for tasters. And if there is ever a question, our team will go back and run the tests again, just to be sure.

But even when that rigorous (and sometimes seemingly endless) process is over, their work is really just beginning. Because it’s not enough to say which product or piece of equipment came out on top—we need to know why. Sometimes it seems random to the rest of us, but these folks don’t believe in that word, so they keep digging and analyzing, consulting experts all over the world and sending samples to labs for analysis, until they find the keys to the particular puzzle. It might be the number of bevels on a serrated knife (spoiler: fewer is actually better) or the processing method used in making a particular soy sauce, but there will be a reason. Once they find it, we can appreciate even more clearly how solid a foundation our tastings and testings rest on.

This all holds true even for the smallest kitchen tools—the testing process has been just as disciplined, extensive, and intensive, because this group has never heard of cutting corners.

The result of all this obsessiveness? You can truly trust our recommendations.