I can talk a little about the differences between the big three companies. I prepared for the interview and received offers from all three offices in one of the European countries. After much doubt, discussion and brainstorming, I decided to join BCG. Here are the main findings of my research on how MBB differ:
1. First of all, by type of work, type of people, exit opportunities, working hours, salaries, etc. These, in my opinion, are the most critical parameters, but they are the same or in many ways similar among these firms.
2. The essential thing that firms use as a differentiator is their corporate culture. And although the culture of all consulting firms is similar in many ways compared to other industries, there are some cardinal differences between these firms:
McKinsey: A clear vision of yourself as the very best. My impression is that McKinsey considers itself the undisputed best among consulting firms. Most of those hired have excellent grades and extracurricular achievements;
BCG: everyone feels like they're working with friends, and it's supportive, and the up and down was very subdued, almost non-existent;
Bain: they have a much higher turnover rate than the other two firms, and there is even a perception that Bain consultants are heavily overworked.
To sum it up, the fundamental differences between firms are minimal. Each has something different: McKinsey has arguably the most recognizable brand globally, BCG has a supportive and collaborative culture, and Bain has fast growth and great people. These things, of course, vary from office to office - this is just my perception.
Good luck to everyone with your choice!