The old adage was if you needed someone to bat for your life, in any conditions against any attack, that man would be Allan Border.
Border recently said the same thing about Kane Williamson, and I agree - the only other player in that discussion would be AB de Villiers - and while Williamson is ranked #1 as a test bat, he's IMO the second best bat in the world behind de Villiers, who is a remarkable talent - although I think the difference is closer than it was - Williamson bats 3 in a shaky lineup, de Villiers bats lower in a stronger, albeit still shaky lineup...
Strange times really, we have some great bats around (e.g., de Villiers, Amla, Younis, perhaps Cook), some likely future greats (Williamson, Smith, Root), others who are very good (Misbah, Warner, Kohli, Bravo, du Plessis, Taylor etc) - yet every lineup is fragile (the Africans largely because of geniused selections, I think, but the rest of us are vulnerable