Emily,
If you take all of the responses you received from both of the threads you started, and set up a tally to evaluate the popularity of the cross options provided, I think you'll see a clear winner. Also, since you've already stated that you have Angus heifers/cows, that means the predominant opinion voiced on this board is crossing them with a Hereford bull. Sure, there were lots of "other" options, but from what I read, the majority suggested a Hereford cross somewhere in their reply. This is also assuming that you want to cross them with another breed.
Now, I still think you need to research the level of demand for black baldy calves in your area. If they sell well, I think the choice is clear.