Which to pay first?

[Stone Jin]

Here is the situation,

My wife and I are at a point where we cannot buy/manage any additional properties.  We are starting to look into paying off mortgages.  The question is should we payoff the ones with the highest interest rates first or the lowest balance first?  Is it better to payoff the 4 smaller loans and get the cashflow sooner, or to payoff the higher rates to save on interest.  Thanks in advance.

Scenario

Property 1 100K owed 5.5%

Property 2 70K owed 5.5%

Property 3 40K owed 4.375-4.75%

Property 5 40K owed 4.375-4.75%

Property 6 40K owed 4.375-4.75%

Property 7 40K owed 4.375-4.75%