I just don't like Moat because it's unreliable hoping you'll have it at the time when someone attacks you (although this is for 2-player - in larger games it's probably more helpful because more attacks are getting thrown around), and it's just not a very good card in your hand. I feel more comfortable just attempting to weather the storm rather than clogging up my deck with Moat.
Black Market is a real joy. It's a card I've ranked higher on this list than it deserves to be, just because it's fun and completely ridiculous.