This all depends on what size company you are interviewing for. Usually, large companies will not ask this question. But if they do, make sure you mention you want to work for a large company because of the resources, the training, and other things you can think of. More likely, a smaller company will ask you this wondering why you would choose a small company. The best way to answer this question is to first think about what a small company can provide over a big company. The most significant advantage of working for a small company is having the opportunity to work on a variety of tasks.