We could prepay our mortgage but are choosing to invest. We have historically low interest rates and would rather have cash on hand than no mortgage. Additionally, meager as it is, the mortgage interest deduction is one of the few we have so we do not want to lose it.

If we were within 5-10 years of the end of the mortgage and wanted to get rid of it before college expenses or retirement, it'd be a different calculus. But for now I'd rather invest than tie up money in prepayment.

Which is a better option? To pay off a home early and count that towards your net worth or save the money. I guess there'd be a good balance - so if you had $100, would you put $70 towards equity and $30 towards savings? - let's assume this is after you've enough savings to last you for 6 months in case of emergency.