I agree with Wucas. The left side would be a very annoying spot. I look many times to my hp/ap when I cw and if I see moving numbers close to my hp/ap it would be very distracting. I go for the right side.
Don't tell me ur gonna watch ur damage every single hit u make, thats pathetic. U only look at ur damage when ur reloading/medding. Thats why the right side is better.