This is the thing that ***** me about this site. Slams is everything apparently. Even if Novak was to surpass 14 slams, would that make him a better tennis player than Sampras? It's hard to say. And impossible to argue either way. You are comparing not only players from different eras, you are comparing different eras.
Even on pure ability alone, impossible to compare. If you gave peak Sampras a racquet and told him to play Novak, and he stayed back and tried to out rally Novak, Sampras will get done like a dinner. But unlike Nadal, Murray and Federer who try to outhit this guy, Sampras is not going to stay back and grind. Who knows how the match would pan out, but I'm confident of one thing, it wouldn't be a 6 hour slugfest. For one, Sampras wouldn't last 6 hours. So he'd be trying to end the points quickly, short rallies etc, so Novak is gonna be taken right out of his comfort zone, with no opportunity to find any rythm and being constantly rushed. So it would be Sampras' agressive style vs Djok's defensive style.
This is why tennis was once a great sport, contrasting styles. Now, whoever grinds better wins.
That is all.