I agree with both Guennael and Udayan. All of the MBB firms are strong across the board. And, like Udayan, I'm biased given my experience as a Partner at McKinsey. Having said that, McKinsey often lost out to BCG in the life science / Biotech / Pharma arena. BCG has a strong focus on the industry. If I were to rank them, it would be 1) BCG, 2) McK, 3) Bain (with a lot of distance between #2 and #3).
It is important as an experienced hire to apply to right office, which means Boston (Biotech) and New Jersey (Pharma) for BCG and New Jersey (and possibly New York) for McK.