For what it's worth, I agree with Alan (except there are several Rolex models I really do like the style of). A watch must, of course, fulfill its primary function of accurately reporting the time. But many watches will do that well, some with in-house movements and some with outsourced movements.
So the "first cut" for me when it comes to choose from among watches is style or design -- a watch that I find attractive. It so happens that I particularly like the style of IWC watches (and a few other makes).
Of course, I'll have no interest in a watch which is truly mechanically unsound. Such a watch would serve no purpose, except decoration -- and that is, to me, insufficient.
But there is nothing unsound about the ETA/Valjoux movements as used by IWC. And while I find a certain satisfaction and pride of ownership associated with a good in-house movement, that's certainly not determinative.