Congratulations on getting such good offers!
I don't think you will receive terribly useful responses - I mean how many people have actually worked at all 4?
Probably what's most important is CV power and prestige, and from that respect - BAH:
Note they order the companies as:
BAH > Marakon > Accenture > E&Y
IN the technology sphere BAH come out on top as well:
I would say this though: these surveys are from an American Careers website. If you check out a UK poll, the story is different:
I don't even see BAH on the list, but i didn't look too closely. Perhaps BAH don't have a large presence over here, I don't know.
Sorry actually - I assumed you were from the UK, where are you based?