Help for a "Lefty" to buy the right circular saw
In my opinion, it really dosen't matter. For certain cuts I need my left hand, others my right. Go to your local store and try handling all the saws. Pick the one that feels best to you. Hint. The worm drive saws adapt well to both right and left hands.
With power tools, where you want accuracy, it is frustrating at times. To counter that, I use a straight-edge as a guide to help me whenever possible ... a speed square or a long, metal straight edge that I can clamp to my work.