Which Forgeworld models are OP?

Forgeworld: Yay or Nay?

I'm not a huge Forge World fan as most of you know already, but all this talk about FW becoming official has got me thinking.  By official, I mean that the stuff FW puts out will be allowed in tournaments and can be taken whenever just like a normal codex option.  Also, the lack of anti-air has a lot of people looking towards FW as possible options.

Before we continue down this path, I want to touch upon my biggest fear about FW models.  I'm all for player options, but I'm not for adding more imbalanced units.  From what I can see, FW does put out a lot of stuff that's fair, but they also put out stuff that's really powerful.  Even more questionable, the units available for the Imperial armies far outweigh the Xenos armies in both power and availability.

With that said, which FW units are considered overpowered?

Should there be a ban list?

If so, who gets to make these decisions, and when does it stop?

Should we start banning Codex units too?

Looks like we're back to permission only again.