What tank has the most self sustain?

[Reynhart]

DRK and WAR have self heals on their two major aoe abilities. Abyssal Drain powered by Dark Arts restores partial damage dealt, as does WAR's steel cyclone. It does it for every enemy hit so doing it in sizeable groups can lead to pretty strong healing.

In dungeons, yes, DRK and WAR can probably beat PLD.

But, against single target, it's another story. The most important part is that PLD is the only job that can massively heal itself out of tank stance. And that can heal someone else.