Three houses which do I pay off? Or should I....

[Chris O'Connor]

Greeting Netizens of BiggerPockets!

I currently own three houses and I think I have enough money to pay one of them off.  I was wondering which of the three I should consider paying off of if I shouldn't.

1.  Remaining Loan:  $117,500 15 year mortgage at 3.25% rent is $1350, mortgage is $1,465

2.  Remaining Loan:  $125,000 20 year mortgage at 3.75% rent is $1450, mortgage is $1,300

3.  Remaining Loan:  $180,000 30 year mortgage at 3.67% Currently live in this one.  

The reason I'm debating paying one off is because I don't think I'll be able to purchase another one having so much debt.  Is there any calculation you guys use when determining which home would be the most beneficial to pay off? 

Thanks for reading and I look forward to your answers!

-lndr