Most people return a refrigerator because it doesn't fit properly in their kitchen. Measure the height, width and depth of the space your new fridge will need. Make sure there's extra space to allow proper airflow around your refrigerator once installed.
Next, consider your food buying habits. If you purchase more fresh foods than frozen, you'll want easy access and storage space in the refrigerator. If you buy more frozen foods, you'll need more freezer space.
Finally, make sure the one you choose fits through doorways for delivery.