Hard to answer because for the most part, the properties are not bought using pure cash flow. 

I would go with whichever one I found the better deal on first.In terms of vacancy a 4plex would be better for the economies of scale.Are you planning to house-hack or is this purely an investment?

I feel it has worked out due to pure luck (appreciation wise), even though it has a neutral to slightly -ve cashflow.

I will continue to rent where I am now and this would end up being purely an investment property. 

Is this pure investment or are you living in one side?

I've spent that last two years preparing, saving, reading and educating myself through BP and several books for that one moment, that moment of pure ecstasy, the  moment I closed on a rental property.

Such institutions provide the necessary processing services to document non-traditional asset investments with an IRA and will act purely as the processing layer.

I rented it for the last 3+ years at $1800 a month (got back most of my investment from rent) and now the sale will be pure profit.

Just trying to decide the best way to quantify a “good deal.”On a pure rental the metrics are pretty easy.

[As a general rule-of-thumb, ex-primary homes reap very poor cash flow, compared to pure investment buys!