Stats - Simple macOS system monitor in your menu bar.
Beaconly - Flexible, easy to use data aggregating menu app that ties relevant information in a macOs menu bar.
iStat Menus - "An advanced Mac system monitor for your menubar."
eul - System & Hardware and OS & Utilities
MenuMeters for El Capitan - MenuMeters for OS X El Capitan 10.11 (and later)
Sidebar Diagnostics - SidebarDiagnostics - A simple sidebar for Windows desktop that displays hardware diagnostic information.