There are a few things to think about before joining the top tier consultancy. First, hopefully the consultancy will put you in front of many customers, so that you can notice their similarities and differences, how they work, what drives them, and so on. This can help you when you are a PM. But if you get pigeon-holed into just one customer for many years (which happens all the time), then you won't benefit in the same way.

Second, the consultancy may pay you very well -- so well that you have "golden handcuffs" tying you to the company. This may be the end of you, though it might be pleasant for a while.

Third, of course having the name-brand company on your resume will open some doors, though it will still be up to you to impress when you walk through those doors.

Could you do just as well in a startup? Nobody can answer that for sure. Both paths have their own risks and rewards.

One way to decide is to follow this saying: Think for today with your head. Think for tomorrow with your heart. What this means is that you should follow your heart into the far future, but it is your head that decides what you should be doing in your near future. Heart being what you love. Head being what makes sense. Very often, what makes sense isn't what you love, which is why so many people become dentists or doctors or lawyers, but then wish they hadn't (of course, many do indeed love those professions, but many started in them because it was the "safe" choice). -- Dan