I've owned several of the Rugers, of all "Marks", and to tell you the truth I don't see any real practical difference between them. One shoots about as well as the other. I'd rather buy a used one than a new one, but only because they cost less generally. I just look for the one with the features I want for the lowest price.
For God so loved the world, that He gave His only begotten Son, that whoever believes in Him should not perish, but have everlasting life.
John 3:16 (NKJV)