The answer will depend on where you are in your career. If you are new, then you want to gain more experience and learn a wide variety of things. If you have a lot of previous experience, you might want to find something challenging and more opportunities for growth.
Short Answers
I want a position where I'll be challenged. I want to learn a lot of new things and I want to continually grow. So I'm looking for a job that will provide these things for me.
I want to gain experience in many areas of accounting. I want a position where things are not routine and where many of my accounting skills are utilized.
In my next job, I want more opportunities to write automation. In my previous position, we didn't have these opportunities because we outsourced this work to other groups.
Long Answer
For the last several years, I have done a wide variety of things. I have set my goals and continually moved forward. I have worked in a time constraint environment, juggled many tasks at one time, and even managed several people. However, one of my goals is to improve my creative side of design. Working for a large company demands a lot of work from each designer. So although creating graphics came naturally for me, I never had the luxury of creating work without being pulled in four different directions. So I want to find a position where I can use more of my creativity.
This is a stronger answer than the generic one about learning and finding something challenging. This answer displays a lot of experience, ability to work hard, and the ability to deliver items quickly. This person answers by saying he wants to find a position where he can use more creativity, while showing off his credentials as a good worker.