I honestly like the look of a natural tail, but I do not compete in Western Pleasure or Halter classes. When I did, I was ten years old and a novice, so my pony had a long, thin, natural tail and his "natural" mane (his mane is only about three inches long and sticks up like a mohawk, but lays in a forward motion so it gives him a complimentary arch - and it's natural!) The judges didn't like it and placed me last.
I HATE the look of a cut mane though. My mare's tail was cut by her previous owners due to it dragging the ground, which is reasonable. Just putting my two cents in :P