I've heard that it's better to max out your reps in one set rather than doing 3 sets of 10. Is that true?

Per the top 5 personal training degree's(NASM, etc..) muscles respond to a stress load. Since they don't have eyes they can't tell 5lbs from 10lbs. They respond to the stress load and send that signal to the brain. That is where you MAP the movement. So in truth, there is no such thing as shocking them, or muscle confusion(PX 90). Certain tempo's that are matched correctly with the right sets/reps will produce the correct results. Meaning a certain speed in the Negative and the right speed in the positive will produce the result. In a quicker and safer time. In your question you didn't put what was you goal or look as to why you would be doing this particular workout.

Chris's answer was spot on. The ultimate answer to your question is "it depends", which is often the answer to most fitness questions! At the end of the day the right sets/reps is all relative to what your goals are. It will probably be helpful to clarify what your goals are so you can receive a more accurate answer.

Thanks for the question!