A list of best Windows tools for system cleaning and optimization:
Glary utilities fully featured, various modules (Clean Up & Repair, Optimize & Improve, Privacy & Security, Files & Folders, System Tools)
CCleaner files, applications, registry cleaner
SlimCleaner fully featured and powerful suite for system cleaning and optimization, it also includes other utilities like Uninstaller, Hijack Logger
IObit Toolbox composed by 5 macro-modules: Clean, Optimize, Repair, Security, Control
Comodo System Cleaner various modules, 3 for cleaning (registry, disk, privacy) plus other utilities (autorun manager, pend delete, wiper, system information, system settings)