Hopefully you should now feel confident in using a decision matrix (either simple or weighted) to help you to make complicated choices.

You might have noticed during my commentary that I was making subjective decisions about which factors were important and what values to score for each option.

That's okay. For an engineering problem you might need to be more rigorous in your selection and justification of the values you use but for your personal decisions it's not a problem.

When you select the factors that are important to the decision, you are carefully selecting what you deem to be the core values of the project - something you may not have considered before this process.

By contemplating why you are assigning each value to each factor, you are approaching the decision in an logical, formulated approach.

Yes, it's easy to rig this decision making process by inflating the values of your preferred option but if you were to do so, what was the point in going through the exercise?

You clearly already had a decision made!