Best borrowing options currently

Looking at purchasing my next investment property and wondering what my best options would be for funding. Houses around us are still going pretty fast and there is certainly a benefit to coming in cash. I have thought about doing a HELOC on my primary as I believe I could have this in place but not pull the money until I needed it? The other option would be a cash out on one of the properties I own free and clear. Looking for thoughts and ideas from the pros. My previous purchases have been either traditional mortgage, land contract or cash so this will be new to me. This will be a single family rental and I will probably be looking for around a 10 year repayment term. Thanks in advance!