What's the best age to start collecting Social Security?

You will receive a much larger benefit if you can afford to delay until you reach "full retirement age" or later - and working in retirement might allow you to do just that. For example, if you take an early benefit at 62 the payment will be 25% less than if you waited until your full retirement age. Hold off until you are age 70 and your benefit will be 32% more than the payout you would have received at full retirement age. So the difference between taking early retirement and waiting until you are 70 can be a benefit that is more than 50% higher.

Of course, the tradeoff is that when you take the earlier benefit you have that many more years of receiving a payout. Still, with much longer life expectancies today, delaying the payout as long as possible typically pays, assuming you make it to at least age 77. And according to the official actuary tables, if you are alive at 65 there's a high probability you will indeed still be around at age 77.