WinRAR is a lightweight, flexible, and easy-to-use archiving utility that can unpack most archive formats, as well as compress to both RAR and ZIP. Free to try for 40 days ($29 for single license), WinRAR is a top dog in the compression category.
WinRAR's interface is about as simple as it gets. Start creating (or add to) an archive by dragging and dropping your files into the interface or by browsing through the Folder Tree side panel (when enabled). From there, the most common functions are laid out in the form of colorful, mostly intuitive icons along the top, which can all be customized by downloading themes from the company's Web site. You can Add files to, Extract, Test, Delete, or even Repair archives right from the main interface. Drop-down menus house the program's more advanced features, including self-extracting archives, archive locking, benchmarking, and autodeletion of temp files.