Tank:
+6 Godplate +20, heavy shield +2. Total +22.
Avenger:
class ability +3. Feat to improve class ability +3. +6 Hide +11. Total so far +17.
So once Dex or Int hits 20 they are equal. Once Dex or Int hits 22 the Avenger is better. Admittedly, the Avenger does pay a heavy "feat tax".
And that's really an edge case, too--Avengers really don't get much out of having a very high Dex/Int, so not only is he paying a heavy feat tax, he's going to be sub-optimal as a striker. And IMHO, at least, being good at your job in 4E is way more important than being a couple of points harder to hit.