David is correct about the left legged classical player. I play classical and use seat the guitar on my left leg. As a result, I set my electric guitar, steel stringed acoustic and mandolin on my left leg. In the early 19th century, Dionisio Aguardo played from his right leg. Fernando Sor played on his right leg but propped the left portion of the guitar on a table in order to create the desired angle. Francisco Tarrega developed the left legged style in the later portion of the 19th century. Most players are taught this way. (Even with this style, you can still reach the end of the neck... I play my srat this way and don't have a problem....)

If you really want an in-depth explanation, Mel Bay publishes a book entitled classical [u]Guitar Pedagogy: A Handbook for Teachers[/u]. Let me assure you, it tells you more information that most humans would ever want.

But, I would think that there is no "right" leg to play on as long as it is conducive to your excelling at the guitar. If you feel you are fast enough and precise enough playing from your right leg, knock yourself out.