This is I know an argument - often visited - with no winners, but do not do down the humble plank wing in the process!
'... Pilatus PC-12s aren't terribly popular as airliners as far as I know. They are primarily marketed as exec ships, and I don't think they are a smash hit there none the less. The Caravan is a rare specimen that runs along the lines of the Beaver and Otter, but it still has yet to find a place outside of very small scale operations (outside of FEDEX) ...'
Both these types are replacing twins in law enforcement in the remotest of places - the wastes of Canada and Australia and undertaking sea patrols off Malaysia and others. In addition operators are pushing quite successfully to get such singles lugging passengers on overwater legs. They will go in - about a year ago a long distance PC12 had an unhappy ending after ignoring a rough engine around Russia someplace, but it is rare enough.
The magic formula for their success is that because where they put the 'rotors' most twin airplanes have dire one engine out performance - but I guess a Chinook with one stopped would be pretty much the same!
It is to toss a crooked coin whether it is better to dunk in a airplane or a helicopter ...... perhaps a rotor would be safer in most instances where you have height but at least it shows that in this 'progressive' world at least there is some reversal of the sinking fortunes of the single at the hands of the deskbound legislators!