You have Kali Linux - every nice pentesting OS to help you get started. Hundreds of scripts and GUIs [Graphical user(friendly) interface]. Than we have Black Box. It almost similar, sleek design. I honestly never really used it since i ever discovered backtrack. This pentesting OS was just recently released. I like very much. Very fast and light-weight. Runs fast even on shitty computers. Very cool look and has all the best scripts and GUIs from back in the day. Parrot OS
Try Backbox OS!
It's great for penetration testing like Kali, based on Ubuntu like Kali, and great for an everyday OS unlike Kali.
Though it may have less tools than Kali.