Yoga and meditation each have their own specific benefits, so it also depends on what you are looking for.
There are many good research articles available online on the benefits of both yoga asanas and meditation, but to sum up a few of the main benefits (when practiced in the proper manner) for your easy understanding:
Yoga Asanas: improve circulation in the body, and the functioning of many organs and systems, such as the digestion, etc. Also removes stiffness, strengthens and lengthens muscles, improves flexibility, posture and stamina. And much more…
Meditation: reduces stress, anxiety, depression, anger, frustration, etc. Improves alertness, concentration, creativity, calmness, perception, and much more…
I would finally like to add that Meditation is actually an integral part of the system and practice of Yoga. As per Patanjali Yoga Sutra, one of the most important texts on Yoga, the system of Yoga comprises of 8 limbs, one of which is Asana (the postures) and another Dhyana (meditation). Both are complimentary, and a part of the science of Yoga.
I hope this answers your question
My gratitude to Swami Purnachaitnaya for sharing his views.