This is a matter of personal preference. Key retaining locks simply provide an additional convenience for rider as they do not need to remove the key from the lock. They can ride with the key remaining in the cylinder. This however, does not make the Ring Lock more secure. In Europe there are certification differences by model: Key retaining = ART2 and Sold Secure; Non key retaining = Varefakta, SBSC SSF and Finlansia, so it is important to choose the correct model if your country or insurance requires a certification.