These are difficult decisions. I can see why you are torn. I won't say one way or other what you should do. There is risk in both options & as an investor you need to weigh those risks & stand firm on whatever you decide.
However, a few things you could do: You could talk with them & learn more of their story to figure out why their credit score is low as well as the type of people they are. Are they good communicators? Are they professional in their interactions? These are good indicators of quality tenants.
You can also adjust how much deposit you take as well. For the 700 credit score you could take 1 month's rent as a deposit but for the other 2 you could take 2 months (as an example) due to the risk factor.
My company accepted a tenant with a horrific credit score because we heard her story. She paid us up front for 12 months of rent & then paid herself each month & at the end of year 1 she paid us for another 12 months...she did this until her credit improved.
Good luck!