There is no easy answer to this question. The higher your down payment, the less interest you will pay over the life of the loan. However, interest on mortgages is tax deductable.
The answer to this question oftentimes is determined by your current financial situation: e.g. just because you have the funds for a large payment doesn't always mean you should withdraw funds from current investments to make it. The best advice we can give is to consult with a financial advisor or tax consultant, allowing them to review your situation and advise you.