How long has either applicant held their current source of income?
If you go with tenant 2, put the third adult on the lease and get them to tell you that he does not have a terminal illness, I have burned by that in the past.
I like to have low income applicants be between 28-31% of income on rent.
I also like applicants who have lived at a previous address 5 or more years, and/or live at all addresses for at least a year. Tenants who move a lot will only cost you money, turnovers are expensive.
Applicants lose points for a banruptcy in the past 3 years. And I only consider collections for items other than medical or consumer debt. Unpaid utilities or amounts owed to landlords are bad, consumer debt explains why they are renters.
Hope that sheds some light. Be careful going below your standards, and always document your objective reasons for choosing one applicant over another. I use an objective point system that provides a score.