I admit I'm not 100% sure, but
Ratchet Bomb was the first card I thought of and I think it would almost always be better than
Powder Keg. True, it doesn't hit man lands, but
Pithing Needle,
Vesuva, and
Krosan Grip can help bridge that gap if they're a concern. I always board in at least one Grip in every single matchup I ever play just as a hedge against something unexpected, and in most matches I'm bringing in more than that. Either has play against tokens and
Chalice of the Void - which was the main reason my thoughts went to Bomb first - but that little bit of extra flexibility of Bomb I think more than makes up for the shortcoming of not hitting man lands. Hopefully I'll be able to test more tomorrow, or else I'll have to see what I can learn at my LGS later this week.