Should I take a boutique consulting offer if I'm still hoping for a stronger brand?

I have a feeling you know the answer to this one :)

But let me assuage some fears (which I personally think is fomo getting to you)

Brand - if you rise up quickly in this company, and show that you've done a lot with them, this shouldn't be a problem (especially with your top-ranked MBA)

Pay - well, you're getting paid nothing right now, right?

Future opportunities - You can re-apply for better consulting firms whenever you want.. I.e. tomorrow..you're not beholden to the 1-2 year timeline

Summary, option 2 sounds pretty reasonable in my view.