Right now, my 3.5-quart slow cooker is making dinner as I work. I mentioned in last week's roundup of 10 back-to-school slow cooker recipes that on the first chilly night, I'd be making Slow Cooker Cheesy Tortellini. I woke up chilly this morning, so out came my Rival Crock-Pot.

Rival Crock-Pots are the brand of slow cookers that most people know. The term Crock-Pot is so synonymous with slow cooker that many people use it as a generic term. However, there are many brands of this handy kitchen appliance and there are also various types.

When you're shopping for a slow cooker, it's good to know how you'll use the appliance.

Good features to have on any model

Here are a few features that are good to have in any slow cooker, based on my experience.

  • A removable crock insert. I don't know if there are any brands that make a slow cooker with a stone crock insert that does not lift out anymore, but some manufacturers made them that way in the past. My very first slow cooker (a free gift for opening a bank account) had a permanent insert. When the crock doesn't come out of the base, the appliance is more difficult to wash. If you're looking for a secondhand slow cooker at a yard sale or thrift store, pass up the ones with built-in crocks.
  • A glass lid. This is simply aesthetics, but I've had both of my slow cookers for about the same amount of time. One has a glass lid and one has a plastic lid. The glass lid still looks nice; the plastic lid is dingy and scratched.
  • A warm setting that you can set manually. Very basic slow cookers will have two temperature settings, high and low. One step up from very basic will give you third temperature option: warm. Make sure that you can manually turn the slow cooker to warm. My 6-quart slow cooker has electronic programming. I can program it for specific cooking times on high or low and when those cooking times are done, it automatically goes to warm. However, if I've determined that something is finished cooking before the programmed time, I don't have the ability to manually turn it to warm. It's the one thing about that particular slow cooker that makes me consider replacing it.

What size do you need?

Slow cookers come in a variety of sizes, from 1.5 quarts to more than 8 quarts. I haven't tested the models in the photos, but they all have good user ratings on Amazon. I have two slow cookers from Rival, a 3.5-quart model and a 6-quart model.

1.5-quart slow cookerThe mini slow cooker, or the 1.5 quart slow cooker, can be used for creating meals for one or two people. It's also the perfect size for cooking hot dips and keeping them hot throughout a party or for melting chocolate and keeping it warm as you work with it. Other uses can be for making small batches of homemade baby food or cooking steel cut oatmeal overnight for breakfast. If you're looking for this type, double check the temperature options. Some of them only have a warm setting because they're only meant to keep food warm, not to cook it.

6-quart slow cookerA full-sized slow cooker can be anywhere from 3 quarts to 8.5 quarts. This size is great for making soups, stews, casseroles and roasts. When placed on the warm setting, the bigger pot can keep a pot of meatballs hot for a party or work as a punch bowl for mulled wine for a crowd. The 3-quart size is often round; larger sizes are oval to accommodate roasts and small whole birds.

programmable-slow-cookerA programmable slow cooker has an electronic panel that gives you the ability to set a cook time and more. The electronic panels usually raise the price of the slow cooker. They're useful if you're not home while the appliance is being used and will automatically turn from the high or low temperature settings to the warm setting when the cooking time is over.

stove-top-browning-slow-cookerSome slow cookers have a removable crock that can be used on the stove top, too. It's useful if you need to brown meats before cooking them in the slow cooker because you won't have to dirty another pot or pan. I could have used a slow cooker like this today when I was browning the ground beef for the Cheesy Tortellini.

triple-slow-cookerThere are also double and triple slow cookers. Some double slow cookers simply have a divided crock and are meant to keep two things warm at once, like dips for a party. Most of the double and triple slow cookers, however, have one base and multiple crocks with individual temperature controls. Obviously, they are meant for cooking more than one food at at time or keeping different foods warm. I had a triple one, but I got rid of it because it took up a lot of space to store and I never found much use for it. But if you entertain frequently, this type of slow cooker may come in handy.

Along with these basic types of slow cookers, you'll find variations. Some slow cookers have a hinged lid so the entire lid doesn't have to be removed when serving. Some have lid locks (like the full-sized one above) for safe traveling and come with insulated travel bags. Other have a hook to place a utensil on. Stainless steel and white are the most common finishes, but they're also made in black and a variety of colors.

Once you know how you want to use a slow cooker, you can choose the size and features that best suit your needs. But remember: form follows function. If a mini slow cooker is red and matches the rest of your appliances, but it only gives you the ability to warm food and not cook in it, it may not be the right choice for you.

Robin Shreeves ( @rshreeves ) focuses on food from a family perspective from her home base in New Jersey.