I would echo wycg's comments above. Most schools previously had used CitiAssist, and that programme has now been cancelled. I'm not sure about the specifics of the loan programmes at the schools that have been mentioned here (HBS, Kellogg, etc.). However I would look carefully to see if their terms (eg. interest rate) have changed. I would personally be doubtful that other schools are able to secure significantly better loans than Wharton, just because I think the schools all have fairly similar risk profiles.
For the record, as others have posted above, at Wharton (as, I'm sure, with most other business schools) there will be a no-cosigner loan for international students. Again, to echo wycg, the question is at what interest rate.
In short, I wouldn't use this as a basis to decide whether or not to apply or attend a school. The loan situation is probably going to be very similar across schools of a similar profile.