So, now several armies have giant monsters. The Chaos Space Marines have their forgefiend and maulerfiend. The Tau have the riptide. The Grey Knights have a dreadnight (and rumors suggest that ordinary Space Marines will be getting something similar). The Tyranids have always had a ton of monsters. Necrons have a giant walker.
So, here's the question: how do the monster match up?
I'm not looking for "my army is great" bravado here. Seriously, how do the monsters match up? Both as tools for their respective armies and in one-on-one duels.
Note: of the giant-monster-having armies, I only play Tau, so if you want me to understand your argument, you're going to have to explain yourself.