Less streamlined than 7-Zip, but with more security features
PeaZip is another open source alternative, but with a few more features in a considerably larger package.
PeaZip's standard installation will make file associations and add context menu options automatically, which you might not want if you're trying it for the first time. Select 'Custom' if you want to make your own choices.
PeaZip is compatible with pretty much every compressed file format there is. PEA, its own format, prioritizes security over compression, with optional integrity check and authenticated encryption. Unlike 7-Zip, it can repair damaged archives.
Its handy extra features include the ability to convert archive formats and test archives for errors. It can't batch compress or watermark images as some of the other tools here can, but can rotate and crop them for you.