WinRAR can unzip and unrar though can't it..? I'm not sure because i use Mac which comes with this Stuffit Expander application and can extract loads of file types...
WinRAR. I've never needed to do something that WinRAR couldn't do, and since I usually use the context menu I don't even have to see the pop-up that tells me to buy it.
WinRAR because it can extract rar, tar, gzip, tar.gz files. But unfortunately, it cannot do the vice versa. If you want to compress a file/folder with a different format, use 7-zip.