I use Kingsoft PC Doctor alongside CIS and find it very useful as it has many useful features for maintaining PC. There are such features like PC health diagnostics, plugin cleaner, scanners for system errors and vulnerabilities (to check and choose available windows patches), startup booster, there are also junk, privacy, registry cleaners and some other modules. That's rather comprehensive piece of software.
The only question I have is about the quality of its malware scanner. Who knows any ratings?