Personally I like the fact of knowing I had my mortgage paid off. But do you think you'll move any time in the next 10-15 years? Would you end up with another mortgage?
I would think investing it in something would be a better decision if that was the case. But I'm like you, I have zero knowledge of investing so I would need to rely on the knowledge of other people I know to help there.
However, how much will be pay in interest over the next X years left or the mortage vs what will be the return on investment in the market? Maybe you are better off paying off the mortgage and investing the savings?