Which Companion would you trust most to save you from a threat?

There have been many companions since the show began way back when, and some have been deemed better or worse in the fandom and public consciousness.

What I am curious about, is which one would you place your life in the hands of if it was necessary? If you were caught on Sontar in a battle between the Sontarans and Rutans, and the companion COULD save you, who would you want there? If a dalek found itself on your street, who would you want turning up at your doorstep to stop the threat?