I have 650K in equity. What's the best way to access it?

[Dumisani Thomsen]

My goal next year is to double the amount of units that we have ( 8 to 16 minimum). Our focus is on smaller 2-4 unit multi-family properties, but I'm not opposed to getting a larger complex. 

I'm trying to figure out what the best way to fund the 20% down payment is. We have cash on hand, but would prefer to keep it, so we'd like to access the equity in our current properties. 

We have around $650k in equity spread across 5 properties including our personal residence. If I eliminate our personal residence, we have around $550k between 4 properties. Our rates for these properties ranged from 2.5% to 3.75% so it hurts to think of the current higher rates, but having the equity just sitting there doesn't seem wise either. 

We've thought of getting a HELOC on one of the investment properties, or possibly doing a cash out refi as well. What are your thoughts on those options? Are there any other creative options we might be missing to access our equity?