I have been following a few posts here that spoke about EY and Deloitte having the same, or similar client list. It seems that people have said that BAS and Deloitte have ftse 100 clients - thus they are equal in prestige. It seems like what clients you serve seems to determine how prestigious the company is. I suspect that the posters in these threads are very junior, and I would like to offer them an additional opinion.
It is not WHAT clients you serve, but WHAT you serve them.
If you take Shell for example, during any financial year, its Shell Centre is always packed with consultants. In my years there I saw McKinsey, BAH, Accenture and EY BAS to name a few. However - they were not there on SUBSITUTE grounds, rather COMPLIMENTARY.
McKinsey was doing corporate strategy, BAH market channel effectiveness, Accenture was doing IT and BAS i have no idea.
It is obvious in todays world that most consulting companies advise the same clients - what the fundamental point is: who does SHell call to tackle its most important strategic issues? Who does BP entrust its SAP to? And who gets called to do the low margin 'routine' work that just has to be done?
THATS what you should think about when you talk to future employers. Be careful to distinguish what they do / against who they do it for!