The key is to find out what malwares and why do you keep getting them? It doesn't help if you just reformat, reinstall, restore the OS everyday, just to get infected a couple hours later. Unless you got nothing else to do.
As OP is asking these questions, it's best if OP look for answers to what malwares are and how they infect your computers. Rather that, than trying every OS and still get infected. No OS is 100% safe. If there was such an OS, no one would ever be hacked (ask the governments)