That depends on your goals. There isn't one single answer. A sound investment for one person is a bad investment for another person. You need to consider what's a good investment for your situation. This will depend on your goals, appetite for risk, age, and investment experience.
A good investment for a 35-year-old business owner might be shares in a growth-oriented business. A good investment for a person no longer working might be high dividend shares, fixed interest investments or term deposits. It all depends on the situation.
It’s easier to define a bad investment. A bad investment is one that you have no idea why you invested, no understanding of the underlying asset or business, no idea of the risk involved and no idea how long you should be holding it.