http://www.anmolmehta.com/blog/2009/09/02/kundalini-yogas-highest-mantra-meditation/ – Kundalini Yoga’s Kirtan Kriya, is considered the best and highest Kundalini Yoga Meditation. It incorporates power mantra meditation, along with mudra techniques (hand gestures) and chakra visualization to work its magic.
Of all the techniques in Kundalini Yoga, this is the one to try if you were given the choice of just one meditation. From the feedback I have received the positive results from serious practice of this meditation has been surprisingly rapid.
The link above gives more details about this technique, including cautions, timings, related meditations, etc.