Have to disagree again on Alonso and Hamilton, sorry. I think this is just Vettel hating, nothing more. Some people resent his (and his team's) success, I don't.
Driver debates can go on forever, and IMHO it's just one factor that makes being an F1 fan even more interesting. I have the utmost respect for Vettel. No hating here. He has, however, been the beneficiary of great fortune, and winning championships is a combination of driving talent and circumstances falling your way.
Senna was arguably the greatest ever, far better than Prost, yet Prost had the better equipment and won more championships. Many would make a similar argument that Hakkinen was every bit as good, if not a better talent, than Schumacher. As a fan of the Scuderia, I was pulling for Schumacher back in the day, but it seems like Hakkienen got the better of Schumacher through sheer talent and determination, whereas Schumacher got the better of Hakkinen through superior equipment/reliability or pit strategy. Sure there were seasons during their rivalry where the McLaren was the faster car, but it wasn't the most reliable car. If Mika hadn't retired at such a young age, I doubt Schumacher would be a 7-time World Champion. Again, it's a combination of talent, equipment, luck, and circumstance that went the way of guys like Prost and Schumacher that at least partially accounts for their success.
While driver talent is supremely important in F1, a great car can make a good driver appear to be a great driver. Can anyone honestly say that Jenson Button was the best driver on the grid during his championship season in 2009? No one in their right mind would have picked him to win the championship at the start of the season. Likewise, let's analyze the 2004 and 2005 seasons for Ferrari. Schumacher won 13 of 18 races in 2004, and finished on the podium in 16 of 18 races. That's probably the most dominant team and driver performance I'll ever seen in F1 in my lifetime. Compare that to 2005, when Schumacher only won 1 race! The Ferrari chassis was so miserably uncompetitive in 2005 that the same driver that won 13 races the year before could barely muster 1 win, and the only reason he won that race is because over half the field parked their cars after the formation lap at Indy!
My point is that the car is every bit as important as the driver in F1, and the greatest driver on earth will never win with a POS car. Vettel could very well have the talent to win in inferior equipment, but he's never had to prove himself in that regard. I'll give him props for eeking out a win with Toro Rosso, but he's had the best car by a wide margin since 2010.
In contrast, Alonso, Hamilton, and Raikkonen are all drivers who have managed to win races in inferior equipment. Perhaps the best example of this in recent years is Alonso, whose Ferrari is so slow that it would barely qualify 6th or 7th, yet he managed to consistently put in on the podium. And if not for idiotic pit strategy in the last race of 2010, Alonso would have won his third championship, which means that he and Vettel would both be three-time World Champions instead of the score being 4-2, in favor of Vettel
Vettel is good, very good, but how good we don't yet know because his car has been so freakin' fast.