It will be hard to find any investment options with better risk/return characteristics than paying down your mortgage. It's also quite tax efficient by construc

It will be hard to find any investment options with better risk/return characteristics than paying down your mortgage. It's also quite tax efficient by construction compared to putting the money in an investment where you have to pay tax on interest/gains (though some countries allow for interest rate deduction from tax anyway). An added benefit is that it makes you more resilient to temporary loss of income etc.