"In my opinion, you should adopt Linux as your primary OS; it's always good that you form a thorough understanding of all the major operating systems- Windows, Linux and Mac.
Well, coming back to Linux Vs Windows, Linux is considered to be mostly virus free. At least it's much more secure compared to Windows. Moreover, most of the software that we use for penetration testing and malware analysis run on Linux.
The Linux OS may not be as popular as Windows, but I can bet that you can do on Linux all that you can do on Windows. And you get the advantage of having better security as well. With Linux, you could opt for a distribution of your choice- Fedora, Ubuntu or Elementary. Kali Linux comes preloaded with lots of penetration testing and reverse engineering software.
So, I repeat, go for Linux. "