Here is how I see it:
Experian strength: amount of trade data on companies. Intricate scoring algorithms. Combination of consumer and business data for sole proprietors - Intelliscore.
Equifax strength: exclusive bank and credit line information which can really help when dealing with new companies. Acquiring more trade data. Here is a sample of their report: http://www.anscersx.com/download/equifax_sample.pdf
D&B strength: Name recognition with upper management. Financial data - but you have to watch the age of that data. Strong on the east coast.
I think every credit department can benefit from access to all these reports. Depending on the type of company or the credit extended one or more reports is your best bet.
For example: 1. your reviewing a new account, a corporation that is less than a year old: Pull an Equifax to see how extended they are with their bank lines, how many do they have, what size.
2. your reviewing a new account, a sole proprietor: Pull an Experian Small Business Intelliscore which combines the principals credit with the company.
3. A company is seeking a very large credit line - pull all three to cover your bases. A less than $100 investment in reports helps you see all aspects of the company.
Another report to consider, if you make your decisions based on tradeline information, is the NACM Report offered through anscers.com. It combines the data from 23 NACM Affiliates and costs $14.95 per report. No contract is needed.