As gwagen pointed out, he really didn't know what gun fit really is until he spent some time and money with a person that knows what gun fit really is and was able to work his "magic" on gwagen's gun.
To some degree, we are overwhelming you with information and you are now looking for your perfect gun. If you are really going to get serious and do a lot of shooting and compete, you will need to have a significant amount of experience before you will buy your last gun. Many folks change guns many, many times before they get one that they shoot for a long time.
If you feel that you can handle an O/U, then try a used Beretta or a used Browning. One of those two guns will feel better (more comfortable / natural) than the other. Then look for a good condition used one of those, with a short, adjustable stock already on it. Spend some time and money on fitting and patterning the gun. Take a clinic from Nora Ross and then shoot as much as you can, for a couple of years. After that, you will be in a position to decide where you want to go in the clays games.