Buy the one you like. The Shield has a much better trigger than the LC. The Shield is a heavier, larger gun. I have an LC and I like it, won't trade it for a Shield. I actually like to carry a 642 revolver because it is lighter than the LC so the Shield is out of the picture because of the weight. I don't have any trouble with the LC trigger but I shoot a lot of revolver and I'm used to the D/A trigger pull.
the 642 is only 3 oz. lighter than the LC but you can tell the difference in your pocket.