Choosing the right carabiner for climbing depends on your needs. If you want quick access to ropes and tools, a non-locking carabiner can make your mission simple. If having the guarantee of the most secure climb, a locking carabiner is your best choice.
In terms of shape, pear-shaped carabiners are best as rappelling and belaying carabiners, while “D” shaped carabiners are best rock climbing carabiners. Asymmetric “D” shaped carabiners offer the same benefits as a typical “D” shaped carabiners but at a reduced weight. They are by far the most popular option for climbers. For aid climbing, oval-shaped climbing carabiners are the recommended choice.