Well its an interesting question about which is safer.
Yes, a vaginal birth with no complications is clearly safer than a C/S.
However, it is not as simple as that.
You have to look at the chances of actually having no complications at all. And to most peoples surprise, the chances of that are really quite low. For a first time birth, its maybe 1 in 3, or possibly even less in some hospitals. By complications by the way, I include significant tears, episiotomies, instrumental deliveries, forceps, ventouse use of epidurals, and everything ranging up to emergency C/S, plus postnatal complications.
Now if you end up with an emergency C/S and in some hospitals the rate of that is 20-25%, then the risk is more than 10 times that of an elective one. And a third or fourth degree tear, while strictly a 'normal' birth will take some getting over too! Thats not to mention later problems with feelings that the birth did not go as you wanted. And of course, pelvic floor damage that might appear later in life.
So yes, a totally uncomplicated vaginal birth is clearly the safest. And if you knew you were guarantted to have one, then there would be no debate. But if you only have a 1 in 3 chance of having one of those, and the risk of any emergency procedure is higher (emergency C/S is 10 times the risk on an elective for example) then on balance, is it better to choose a known low risl over a potentially lower but potentially much higher risk? it actually is a very evenly balanced risk/benefit question.