One Person Boutique vs. Corporate Finance arm of Accountancy Firm

Hi all,

I have a career advice question.

Background:
Current MSc in Finance student looking to break into IB in the near future.
In the coming weeks, I will likely receive two offers from two firms in my mid-sized European city.

Firm A is a basically unknown one person boutique looking to expand, founded 1-2 years ago, headed by a person with +10 years experience in an EB. We get along very well, the recent deals seem to be interesting and I know it will be incredibly hands on. I really like the idea of working here. 15min commute.

Firm B is a little known accountancy firm, founded ~6-7 years ago, with +100 offices, backed by PE and I would be working in the corporate finance division. Probably a ~20-person team. No information on previous deals, is that a red flag? All the partners are accountants, I'd also sit the accountancy exams, whereas in the other firm I would not. 1.5hr commute twice a day.

What's my goal?
My goal is to work in one of these firms for 6-12 months and successfully lateral into a bigger MM investment bank. Which of these firms do you guys think will be better suited for that transition and which do you think will be a better learning experience?

My gut has been telling me the one person boutique is a better option but I'm not sure if it being so small & lesser known will be a problem.

I would greatly appreciate your feedback and advice.

Thank you!