I believe that both having an imagination and having the knowledge to build from that imagination are key. A person may have all the knowledge in the world but a lack of creativity or thinking outside the box will likely keep them from making relevant use of that knowledge. Vice versa having a great imagination is a wonderful thing but if a person lacks the knowledge and practical ability to use or make what they have imagined then its fairly useless.
When Einstein claimed that imagination is more valuable than knowledge, he was extremely accurate. Even people who are very intelligent and smart sometimes lack creativity. Therefore, he or she is not as worthy to society as someone who has a vast imagination. For example, if someone is an amazing engineer, he or she could really benefit society. Even more so if that engineer is also very imaginative and creative.
Knowledge is the outcome of imagination, Simple as that so why is this even a question?
We always wonder why these Opinion debates are pathetic and my first assumption because they either failed to look up an older debate of the same question or did not know how Google works.
However it's mostly because they want to stir up another crappy question for not much reason.
I believe Albert Einstein's assertion that imagination is more valuable than knowledge. Learning requires an imagination because the mind has to imagine and act new ideas which can sometime reshape prior knowledge. If you can't imagine, then you can't learn or gain knowledge. More scientific questions are created with the imagination.
I don't think you would want to be a person possessed of one but not the other. Imagination is important in the arts and even in the sciences. Knowledge is also important in both the arts and the sciences. The person who is equipped with both a fertile imagination and extensive knowledge is in a much better position to realize high accomplishments.