I hate artificial plants in my tanks but I have a few anyway. The real plants provide a nice look that changes and matures over time. They remove impurities from your water and provide a minor bonus in oxygen but that just means the oxygen stays where it should anyway with good circulation. If you have enough plants, compared to the number of fish, they can act as the only filter in a tank. Real plants such as the mosses and floating stem plants make a very nice cover for my livebearer fry so that I don't need to constantly fuss with things like breeding traps.
Real plants also require good lighting and that same amount of light can lead to having algae in the tank. If you keep large cichlids, the constant digging of the cichlids make the real planted plants a PITA. In that case the silk plants are my second choice because they look more like real plants than the plastic ones do. Even if you have cichlids that dig, the mosses and floating plants can still be used but they are not as decorative as the planted plants.