To make the perfect poached egg, I always use a medium sized non stick frying pan, fill it 3/4 full of water add vinegar. The place on cooker, (full heat ) bring to the boil, then add the eggs and reducing the heat to medium at the same time, this allows the eggs not to over cook and form the perfect shape. I then boil for 7-8 minutes until finished as soon in picture.
Also, try to us free range eggs whenever possible, the cost is minimal for the taste and quality when using free range egg's.