The correct answer is: "What do your sales people do on a day-to-day basis?"
"What CRM system are you currently using?" will result in a short answer that isn't going to tell you much. Even if you're familiar with the competitive product, the only way to proceed at this point is to rubbish the other product, which is going to make you look bad. This is not to say that this question couldn't work, only that it's not the best choice.
"What could your current system be doing better?" might produce some useful information, but you're asking the prospect to diagnose the problem and come up with the solution. Isn't that your job? And, once again, you're starting out by rubbishing the competition. And you really don't know enough about the situation to strongly position your own product.
By contrast, "What do your sales people do on a day-to-day basis?" opens a dialog that allows you to better understand the situation and gradually uncover challenges that you can address better than the competition. As the conversation progresses, the competitive stuff will emerge, but you've put the focus where it belongs -- on the larger issues of the customer's real needs.
It's not that the other two questions are "bad." They're actually useful, but this is not quite the right time to bring them up. The competitive questions will be more meaningful once you know something about the environment in which the products are being used.