.- Access to funds: I could consider a cash-out refinance or a HELOC to access funds for additional investments.- which property would you recommended me to keep? 

I have purchased one duplex using my own money and am looking to scale but wanting to leverage OPM or low or zero downpayment funding options. 

One of the SF (which if I go this route will be my starter home) is at the heart of my city within a 10 minute drive from almost EVERYTHING while the second is a bit on the outskirts and near all of our oil and gas company's (hundreds as per google).  

Some people use their IRA to fund fix and flip's and keep the profit in them tax free. 

Many people in the past few years that were simply raising money for funds or syndications, are now in serious legal trouble.

One of the more overlooked downsides is the funding fee; however, if you have a service-connected disability rating, the VA funding fee is usually waived. 

I'd suggest staying away from the typical TK companies. 

Given your credit score and ability to fund 25% of the purchase I don't foresee any obstacles you will face. 

Permitting can become a bottomless pit your funds go in never to be seen again. 

Since the average company lifespan is 10–18 years, most private-sector jobs your current tenants hold will disappear in the foreseeable future.