Fanaelialae
Legend
If I recall correctly, the designers have said that they intended dragons to be the strongest enemies in the game. Additionally, the Ancient red has a CR of 24. If you're fighting something whose CR is four greater than your character level could ever be (20 level cap), then every bonus HP or +1 of AC that you can get counts because you're already trying to somersault up an icy slope.
If you have an AC of 25 (quite respectable) then Shield is fully helpful against any creature that has a +10 or more to hit, and somewhat helpful against anything with a + 6 or more to hit (because they will always hit on a nat 20). There are dozens of monsters with a +6 or better to hit, including the CR 2 Ogre. Also plenty of creatures with a +10 or better, including the CR 9 Fire Giant. So it's not just the most powerful enemies in the game that will be able to hit the fighter. That's bounded accuracy. Unless the DM hands you every AC boosting item in the game on a silver platter, there will be plenty of things that can hit you, so having an additional +5 AC is nothing to sneeze at.
I recall that. I am arguing that the added breadth doesn't equate to the value of a character level.
Fair enough, though I don't agree.
Sure, but the F20 can shove a target prone to effectively eliminate the benefit of shield and then make the same compliment of attacks that the F19/W1 could.
Even better, the F/W doesn't need to waste attacks on Shove, thanks to Shield. After all, there's no guarantee that the F20's first Shove will succeed. Given that both fighters have a Str of 20 and are probably proficient in Athletics, his chances of success are about 50/50, although F/W wins ties. Which means that F20 will probably need 2 attempts to knock F/W prone, leaving him with only 2 attacks left. Meanwhile, F/W is hitting him 3 times with the same accuracy. I'd say that's advantageous.