I try to make all the `ai_playValue`s unique, so this should be either slightly more or less than Mountebank. If an AI has both Mountebank and Soothsayer in hand, and only one action, which should it play?

I'd guess it should choose Mountebank because it has a benefit this turn. Of course this really depends on whether it wants +2 coins this turn, but checking that is slow.