I'll ask you this: Are you a savvy investor who keeps their eye on the ball?

Looking for some insight if I should wait to purchase in the hopes of more multifamily properties becoming available in the future, if I should make an extremely low ball offer on what's currently listed.

If that is too low for them then you've put the ball in their court for them to give you a number they are thinking. 

If people drop the ball or make mistakes in that process it can take 5+ days to get the money which means your contractor can't start back up until the money comes in. 

Country subdivisions are cash snow ball type investments.  

It seems like interest rates are most common, so that’s what I’m leaning towards, but is the ball in my court regarding the terms or in the investor’s?

If your intent is to sell your rental(s) and leave the RE asset class then I suppose the # years of cashflow metric might be more applicable, but I think it heavily relies on the assumption that you've accurately timed the top of the market which requires a crystal ball and sorcery above my pay grade.

So whatever gets the ball rolling fastest is the best route for you to take.

Looking for some insight if I should wait to purchase in the hopes of more multifamily properties becoming available in the future, if I should make an extremely low ball offer on what's currently listed.

AIRDNA has it's place, but it's no crystal ball.