GMOs: beneficial or deadly?

Definitely, a third arm. A third arm, if it's not an ugly, rudimentary appendage, has excellent functionality that will help not only in everyday life but also in some types of professional activities. A third eye, on the other hand, has various features, depending on where it is located. If it's next to the other two, it's completely unnecessary. If it's on the back of the head or on the side, it only provides a slightly wider field of vision, which can be adequately compensated for by the ability to control the other sensory organs. Besides, it won't be of much practical use in life. An eye on the tip of a finger? That's more interesting and useful – it would be easier for dentists to examine a person's prostate and oral cavity, a voyeur could slip the eye under a door, and a spy could peek around the corner without being noticed. But, in my opinion, the functionality of a useful 24/7 arm is still much higher. An eye on any other surface of the body is pointless, as the body is covered in clothing. As for a leg, it's hard to determine what it could be useful for. Having a better support? Riding a specially designed three-wheeled sand trike? Jumping down a mountain on three skis?