I'd say start the process of securing your HELOC if you havn't done so and spend time analyzing deals and determining what type of investor you are looking to be. 

Start by analyzing cash flow and market demand for each property to decide which one to rent out.

DSCR (Debt Service Coverage Ratio) loans are popular for real estate investors because they focus on property cash flow rather than personal income.

Experienced investors typically value properties like yours by analyzing cap rates, cash-on-cash returns, and income growth potential.

You need to learn how to analyze property and determine if they are a good investment.Here's a guide that describes how to analyze a property.https://www.biggerpockets.com/blog/rental-property-cash-flow...

All others are month to month or expiring this year.I used a spreadsheet I typically use to analyze a financed deal.

There are a bunch of different figures associated with this decision, such as new interest rate, old interest rate, cash flow of new property etc, but I'm having a hard time getting my mind around how to analyze the decision mathematically.  

Quote from @Avani Patel: Hello, it is really time consuming for me to analyze each property by manually entering its data to calculate the return. 

BiggerPockets also has a calculator to analyze deals, and I highly recommend you start this as soon as possible, even if you are not ready to buy.

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