the reason why corporate/VIP like celcom because
they have special department handling corporate/VIP(with title) for their customer service...
and also celcom is GLC and of course GLC company will SUPPORT another GLC company

p/s:
i have experience using both celcom and maxis...
and i like maxis much better in term of their service...( do remember that i'm just an average joe without any title or corporate jobs    )
but ONE THING FOR SURE is currently celcom has the widest coverage in malaysia...