How will you use it? If you want a food processor mostly for small jobs like mincing garlic and herbs, you might be better off with a mini chopper. If you plan to do a lot of cooking for a big crowd, by contrast, you may want a bigger machine that holds up to 14 cups. (For most home users, experts say a 7- to 9-cup capacity is usually sufficient.) If you need to prepare both small and large batches, then you might choose a full-sized food processor that comes with a mini bowl for smaller jobs. You should also focus on how the food processor performs at the jobs you intend to do most often, such as puréeing baby food or kneading dough. One job most food processors have trouble with is processing large batches of liquid, so if you need a machine primarily for soups, a good blender might be a better investment. See our blender report.
Where will you store it? Larger machines tend to be heavier, making it difficult to retrieve from a cabinet, thus, begging to be stored on a countertop. That said, bigger appliances also require more counter real estate. Don't forget that attachments, such as spare blades, need to be stored too. Some models include cases for this purpose. Keeping sharp blades securely stowed is especially important for those with young children.
How will you clean it? Many food processors have dishwasher-safe parts -- bowls, blades and other attachments -- that can make cleanup much easier. If you don't have a dishwasher, however, it's more important to find a model that can easily be washed by hand.
One newer option in this field is the food processor/blender combo: a motor unit that works with both a blender jar and a food processor bowl. At this time, however, most models in this category don't get very good reviews. One exception is the Ninja Master Prep Professional QB1004 (*Est. $60), which has a 450-watt motorized lid and blades that attach to a bowl or pitcher made of BPA-free plastic. In a professional test, the Ninja Master outperforms all mini choppers, with great results for grating, chopping and puréeing. Owners say this unit is very versatile, good for everything from making milk shakes to mashing potatoes to, amazingly, grinding venison. However, some owners report problems with durability. A truly reliable blender/processor combo may still be some years away.