For me, modern F1 drivers need to do much more to be considered a 'great' or 'greatest'.
Firstly, it is not realistic to compare them with a driver like Fangio, who drove with hardly any protection, little or nothing in the way of a seat belt, extremely poor tyres, bumpier road surfaces, dangerous barriers and zero runoff areas.
So anyone considering Fangio or a driver from his era to be the greatest has a strong argument.
Then, moving on to the 70s/80s/90s, the speeds became much higher and the risks were still very high, with famous high speed dangerous circuits/bends like the final turn at Mexico or the high speed old Silverstone layout, which have since been removed or dumbed down with chicanes, revised bends and tarmac run offs. So the likes of Senna, Prost and Mansell can also be considered as the greats.
And you can use the same argument for Clarke/Hill in the 60s, Stewart/Ffittipaldi/Hunt in the 70s, and definitely Lauda would be high on the list.
This is only my own opinion, but these drivers, including Mansell's single championship, and certainly Senna's three, are easily worth a good handful of modern day titles.