What best suites my situation, Conditional Waiver & Release on Final Payment or Unconditional? *(I'm the Home Owner)*

I hired a contractor to do work in my house. I paid him 50% and he didn't complete 50% of the work. He doesn't answer calls anymore and continues to give excuses why he can't come and is down-the-roading the project. He's way outside of the terms of our contract. I don't want him to turn around and say that I don't want to pay the balance and then he puts a lien on my property. So i want to protect myself against him placing a lien on my property for the remaining balance. Do I file a Conditional or Unconditional Waiver & Release on Final Payment?