If you are looking for the most realistic flame that resembles a wood fire, vented logs are your best choice. These produce tall yellow flames that wrap around the logs creating the natural warmth and ambiance of a real fire.
Vented logs need to be installed in a fully operational wood-burning fireplace as these logs do not burn the gas cleanly and generate some exhaust that is very similar to a real wood fire. Therefore, with vented logs the chimney vent or flue needs to be open to allow any air to escape up the chimney. The advantage of a vented system is that fires need oxygen to burn. These logs produce some soot when the flame touches the log but do not require much cleanup.