At least our Terminators are amazing. If we got 3+ invuln saves on our storm shields, we'd still be the best terminators in the game, and even now we're only outclassed by a bit of fancy wargear in the new codices.
Basic Grey Knights, though, pay a ton of points for a bunch of worthless special rules, and lack certain vital options like frag grenades (inquisitorial storm troopers have frags, but Grey Knights, the elite of the elite of the elite of the elite in the Imperium don't?).