Dear Charles--The higher your down payment, the lower your interest rate, hence, making your payment more affordable for you. So, without know your situation, it is difficult to advise you on the best interest rate for you. Do you want to leverage your funds for investing? This would call out for a lower down payment. Do you want to maximize interest write off for your taxes? --lower down payment, etc., etc., etc. Have you sought the advice of a professional financial planner, preferably someone with your same goals and aspirations. That's a good place to start.
Decide before your loan is finalized. It's very expensive to change your mind further down the road.