The first qualified applicant will probably be the gov’t for section 8 use...
What happens if you rent to the first qualified applicant, and a bit later the qualification turns out to be bogus?
Will the second qualified applicant make a legal complaint?
Section 8 tenants are easy to avoid, you just write into the application that they must be able to take possession of the apartment within 14 days or so of the application being approved or the application is cancelled. Section 8 requires all sorts of inspections after the approval and they will never get them done in time.
Of course they can reapply, but hopefully by then you have found another applicant and can tell them the apartment is no longer available.