Depends on your programming capabilities, how much you want/can pay for it, how much of your time you want/can invest in it, what kind of tradingsystems/traing-frequency you got, what datafeed/brokers you want/have to use, what market you gonna trade etc.etc.etc.
Different traders/systems have different needs, and as such there is no software that can generally be considered "the best".
When you have answerd all those questions, and carefully compared the different auto-trading products, its likly that you will find that none of them does all you want and is compatible with your preferred brokers/feeds. Solutions that look good on paper also fail often on allegedly "small" issues. Its a long, hard and often very frustrating way to get there.