Sometimes life can be easy and other times it can be more difficult..and so it is with erasing backgrounds. In cases where you have images specially prepared by a stock photo agency or you've shot it yourself on a plain background, erasing the background behind your subject will be easy:
The magic eraser tool can be a nice choice for getting rid of a background that is very simple and is very different in color or brightness from your subject. It works and can be configured like the magic wand tool, but instead of making a selection that you'd then have to clear the selected pixels, it simply erases them straight away.
The background eraser tool is very similar to the magic eraser tool, but can be limited to a brush size and have soft edges like the regular eraser tool.
The regular eraser tool will work when you have a background that isn't simple and different from your subject, and you certainly could use the background eraser tool up to the point in your image where your background becomes more complex, and then switch to the regular eraser tool.
In those cases where your background isn't simple or different in tonality and color than your subject, you'll just have to spend some quality time with the quick mask mode and zoom way in!