I have an offer from XXX, but am not done interviewing with other firms.
Can we, lowly ACs or BAs, leverage different offers against one another?
For instance, will I be able to go to XXX and say, "I'd rather work for you, but ZZZZ is offering me more money? What can you do?"
I'd be very, very careful about this, especially with the top firms. My first reaction if I were on the receiving end of the comment is, "Whoa, we made a mistake in extending that offer, maybe we should rescind it."
Basically the top firms don't want you picking their firm only because of the money.
The one situation that does come to mind where this might be appropriate is if the offer is from a boutique firm and you also have an offer from a Top 3 firm. If the boutique is accustomed to stealing away people from the top firms, they are probably already accustomed to paying a lot more.
For example, when I recruited, I got seven offers and ended up picking the one with the lowest salary -- that would've been McKinsey.