Autoruns is my go to for this subject. However it has been previously suggested to allow ccleaner to add entries. While I disagree that this should be added (ccleaner is about removal not addition) the Developers do take into consideration all viable suggestions.
Honestly because startup items can be added just by dragging and dropping a shortcut into the startup folder, I find the idea of a program adding them unpalatablele.
I've wanted the ability to add in programs myself. It could come in handy if for instance someone accidentally deletes something via CCleaner, then they could add it back in.
That brings up another question and feature request, since CCleaner can delete startups, why does it not offer to make a .reg backup of the startups to very easily undo the changes?