If you have the money, the answer is 100%. It is always a good thing to buy in cash or put down as much money as possible to avoid a monthly mortgage that you owe forever.
You should always aim for at LEAST 20% down payment! This is how you can avoid that Private Mortgage Insurance (PMI). If you cannot afford the 20%, put any lower than 10% down.
Extra fees and interest can cost you more than you think!
Just to put a number on things, for a $300,000 house you should save $30,000 to $60,000 for a down payment.