I have heard some people say steel containers should never be used in the refrigerator, while others say steel is the best. Which is correct?
There is no problem with storing food in (stainless) steel containers. In fact, most gastronorm containers you see used by professional kitchen are made from stainless steel.
This doesn't mean that they are somehow "the best" - they are as much suited for storing as many other types of container. If you have some special requirements, you have to find out what offers the best tradeoffs for your preference. If you don't, then it doesn't matter if you get stainless steel or something else that is suitable.
The above assumes that your containers are non-reactive. This would include stainless steel, or containers which are surface treated, for example emailled. Naked blue steel will likely react with many foods, so it is not a good choice. Blue steel which has been seasoned at home will also have some reaction with food, even though more slowly than naked, so it is used in pans, but not in storage containers.