Governor: ridiculously overrated
Can you explain?
I've been finding that spamming Governor (for Gold) keeps winning me games, especially if my opponent doesn't value the card as much. The ability to get double Province turns ridiculously early is pretty spectacular. Of course you can only safely use the +3 cards on the last turn, but that should be a double (or even triple) Province turn to close it out. I will do +3 cards earlier if I'm reasonably confident it will be a double Province turn and my opponent doesn't have an engine that can match that, even with an extra card.
And this route to victory is fast - in the absence of cursers, the games end around turns 11-14 with a majority of Provinces gained.
To answer the OP: I think
Navigator may be slightly underrated. It's pretty nice in a heavy attack and deck clutter game with no good trashing available. The $4 price tag is just right in that environment, as $5+ can be difficult to reach. With bulky decks filled with crap, the +$2 is also pretty nice, and the ability to discard the next hand of (Curse, Curse, Copper, Copper, Estate) can be a virtual extra turn. Might make the difference in a low-money game that's going to end on piles, giving you an extra shot at those Gardens/Duchies/Islands/Tunnels.
And speaking of Tunnel, Navigator is one of the best enablers. But note I do still think it's a pretty bad card, just not *that* bad.