Refinance Question - which house to pick?

[Carl Simon]

Hello, 

I am seeking advice and guidance on what criteria to use when refinancing an existing rental buy-and hold. I am seeking to graduate from the beginner level and start to pull money out of our current 6 property portfolio to keep growing using the velocity of money concept.  What factors to others use when deciding which properties to seek refinancing on:

- Equity in the property (more the better)

- Interest rate (higher than less of a loss to refinance)  

- Years left on loan (longer the better since we are re-starting the clock)

Or am I going about this wrong and should seek a portfolio loan across all of our properties? 

Thank you, I am eager to hear how others go about deciding which property to refinance and when, and what factors are the most important to this decision making process!

- Carl