Here's what you say... it's a visionary company that's been around a very long time and isn't going away, it reinvests its revinues in research and development and leads the industry in innovative solutions, the people who work for Corning are happy and get along and focus their energies on the customer, and there are many opportunities to grow in every job and move on to a variety of careers including sales, marketing, production, product line management, etc. Tell them how you see eye to eye with Corning on these issues and are excited about the career opportunities. Don't mention other companies by name unless the interviewer brings them up. Be honest if you are asked if you are interviewing with other companies... don't worry -- it will not make you look bad, and the interviewer will start telling you "Why Corning" because we love the opportunity to get on our high horses and talk about how great Corning is.