In reply to Pesda potato:
Think it's pretty normal for your dominant foot to be shorter and wider as it tends to have a stronger arch.
My arches have got higher over the years due to consistent strength work etc, so foot shapes do change.
I always found the key was to buy something with a very roomy toe box but good lacing that goes down low on the foot. If you can really tighten the shoe very firmly across the top of your foot, it will stop your toes from sliding forward and hitting the front. A wide/roomy toebox will allow you to combine that security with room for your foot to spread out and do its work when striking the ground.
I've never had toenails come off, but have had bruised nails in narrower shoes or when running in the wet without stopping to get the additional slack out of my laces.