I'd have to count whatever we couldn't come to terms on or deals that ultimately fell through or we walked. 

So if you let a relative use it for free or cheap, that counts against your personal use days.  

So what I've gathered from all the responses is that real estate with very low maintenance and a dense count of "renters", that use that property tends to cash flow the most.

Or do I need to have already around 20% equity on the SFR for it to count?

On a listed property you can't count it out.

I'm not counting on getting all of those properties off of the MLS. 

Make sure to count for closing costs and realtors fees on the back end, and the unexpected rehab costs.

If you've got a duplex at $1000/unit and somebody moves out you're only bringing in $1000/mo until you get it filled.  4-plex is also the highest unit count you can go and stay within the Fannie/Freddie lending guidelines.As others have mentioned, the multifamily market is pretty hot right now.  

This is currently my only good cash source(CC's don't count as "good") until new income is established I wouldn't want to max out the loan on rehabs unless it was exceptionally justified but could spend 5k-10k and feel solvent.I had to quit my job and leave the area last fall without having the time to make an informed decision on the house. 

That is where equity comes to play.To add insult to injury, not only do vacancies go through the roof, but prices in the less desirable neighborhoods tend to get hit first and the hardest in a recession.So, to summarize, quality of cash flow counts as much as quantity, and that is mostly to do with the quality of the neighborhood.