Which is the best posture to Practice meditation? Does any one know, which is the best posture to be assumed for practicing meditation?
Bhikkhus, the bhikkhu following the practice of my Teaching, having gone to the forest, or to the foot of a tree or to an empty, solitary place, sits down cross-legged, keeping his body erect, and sets up mindfulness, orienting it.
Then with entire mindfulness, he breathes in and with entire mindfulness he breathes out.
Maha-satipatthana Sutta

The above is the standard posture for meditation (i.e.: sit down cross-legged). Even though I can't remain in this posture for a long time due to back pain, I personally believe this is the best posture for meditation. Having said that there are many other postures suitable, depend on your situation (walking, sitting, etc.).