However, the fact that she has a significant amount of negative equity ($100k) would kill it for me.  

Those are going to be seriously cash flow negative, so there is no prospect of buying these for income

Let's not turn this into a pit bull debate and politics as it has been discussed at length in the past.For every statistic that someone can show them as lovable and huggable then another can show the exact opposite.I have had varying animals all my life so know a lot about them.

Please tell me which one and why and also if you are willing positives or negatives if either.

As a professional "analyst" and operations manager, I develop statistical real estate investment models in Excel. 

PITI on this house is $1764/mth (assuming 30 yr fixed 4.022% APR 2.9% property tax $828 anual insurance) meaning investors would expect negative cash flow of $714 per month.

They might have a great algorithm, but it doesn't take into consideration the elementary school abutting the backyard, the freeway a block away, an overbuilt or underbuilt house, that in some neighborhoods a pool actually is a negative value, a garage converted into a bed & bath, a one car garage in an area of two car garages, etc. etc.

Over time they would have been cash flow positive, but at that particular point in time they were cash flow negative, and underwater.  

I have another thread going about whether or not to sell my property that has a negative cash flow.

I hesitant to refi and add more negative equity with closing coats, as well as start the