How would Sauron fare?

[Numenorean]

Let's just speak strictly militarily. At the time of the Siege of Mordor, Sauron had enough strength to withstand a siege of the largest group of warriors ever assembled for 7 years

Interesting thread Lord of Angmar, but was the force that Sauron had assembled by the end of the Second Age smaller or greater than his apex at the end of the Third?
I mean, I always understood that despite victory at Pelanor, Aragorn and the Captains of the West were heading for certain military defeat at the Black Gate, Saurons forces were quite simply, Legion. It took the destruction of the Ring and the total undoing of his power to halt his seemingly inevitable victory (due to vast numbers+general diversity of powerful evil units etc..).
So was Sauron - just prior to his Ring being flipped - more or less powerful than he was at the time of the Last Alliance of Elves and Men?