Three Applications...who to choose??

[Robin Cloud]

Hi. I own a duplex property (I do not live on site) and I'm renting out the 2 bed/1 bath back house. I got three applications today. All of them are financially qualified and sound:

1. Single woman, mid 30s, small dog, 50k in student loans, decent savings, 735 credit 

2. Couple, unmarried, two cats, 50k in savings, mid 30s, credit over 780!

3. Young couple, late 20s, only one is steadily working but make 130k, partner would be the occupant, no pets. 705 credit but only because she doesn't have a lot of credit. 

Torn between 1 and 2. Thoughts?