Neither label automatically wins. The stronger platform is the role that gives you better evidence of structured problem solving, measurable impact, senior exposure, and progression, while also building a credible reason for why you want MBB later.

A boutique can give you direct client work and consulting-style problem solving, which makes the transition story straightforward. An internal strategy role can be equally strong if you own important analyses, work with senior leaders, and develop expertise in a sector MBB values.

Compare the actual jobs: project quality, mentorship, brand credibility, analytical depth, and whether you will have stories that demonstrate leadership and impact after one or two years.

Choose the role you would still value even if the MBB move never happens. Then build a strong record there rather than treating the first job as a temporary holding pattern.

I would compare the actual work before the labels. Some boutiques are way more client-facing than internal strategy roles, and sometimes the reverse is true.