I actually am going to LBS this September
As far as I am concerned, LBS has a stronger finance focus whereas INSEAD, with its case-based approach, has a strong recruitment in consulting and general management. Really, if you are interested in marketing, LBS might not be the school for that. It also depends on what kind of tier school you are looking for and this will help you narrow down your choices. Perhaps pick one ultra-elite, 2 elite, and 3-4 safety schools. The top choice should be Kellogg, followed maybe by Virginia(case based) and UCLA or so. For the next 3-4 schools, you will have to do your research as to which school is more marketing inclined. Once again, others might give you their point of view.