Something I've learned over the past 20 years is that there is no perfect sales question. However, there is a series of perfect questions.
These questions uncover your prospects' current situation, where they want to be (their desired state), how problems are impacting their businesses (or themselves), what they expect from a solution, the way the decision-making process works in their organizations and the nature of potential roadblocks.
If you ask questions to uncover these pieces of information, you should be able to position your solution in a manner that resonates with your prospect. But here's the catch: You must pay careful attention to your prospect's responses and be prepared to ask on-the-spot questions to further drill down and get clarification.
For example, if your prospect says, "It's costing us a lot of money," it's imperative to summon up the courage to ask: "Exactly, how much money is it costing you?" This may sound simplistic, yet in the sales conversations I have witnessed, it seldom happens.
So while there may not be a single perfect sales question, a series of high-value, thought-provoking questions can absolutely help you close more sales.