Both tour lines are good, however, it takes much more than the 1h supposed time to do one loop. Be aware that many buses do not have shades upstairs (and it's always hot or rainy or both in SG!), only a few have it at the back. you are not allowed to stay on the bus once you reach the final stop (which is also the departure stop), the staff forces you to move to another bus even if you just boarded a few stops before and that you don't mind waiting for 20mn for the bus to depart. A lot of the audio guide didn't work and the driver can't be heard through the microphone when he makes announcement, so you need to make sure you know where/when to stop. This being said, both lines offer a great tour of Singapore, and we always enjoy doing it when we have family and friends in town.