I find thread title a bit misleading. I consider majority of F1 grid as very talented drivers. For example, Hamilton or Vettel may be a tiny bit more talented than Sutil or Pic, but I still consider Sutil and Pic talented. Even if you have plenty of financial backing from the beginning of the career, there are many others who also have, so to be in F1 instead of all of them and be within a couple of seconds of the very best drivers in the world you need to have a big talent.
But I reckon you mean the best drivers who failed to score a single WDC during his career? Yeah, Gilles Villeneuve and Moss seem to be obvious choices. Von Trips and Cevert were looking good for a title if not their fatal accidents (pretty much like Villeneuve). Frentzen also had a couple of very impressive seasons, but he failed to deliver when he's got his chance.
If Rosberg doesn't luck with circumstances, he may well be added to this list. The same goes with Hulkenberg, who, I have no doubt, is capable of race wins in right car, but wheter he gets an opportunity for WDC during his career is another matter. But well, both have around 10 years to earn their WDC so it's quite early to speculate about this.