People are of the opinion that its better to deal with the original creditor as long as possible. You can also negotiate a 'pay for delete' with the original creditor. However, some collection agencies too can do 'pay for delete' , hence it never hurts to ask.
A delinquent account would stay on the report for seven years and unless you successfully negotiate a 'pay for delete' it would remain as 'paid as agreed' or 'settled' no matter with whom you have settled.
The creditor would report the account as 'charged off' if they have turned it to collection and the account would appear against the collection agency's name.
Hope it helps.