Photoshop designs vs Prototyping, What do you prefer in your UI development process?

We are a small Frontend team of 2 members stuck with a decision that we need a designer or not.

We both have the same opinion that getting PDFs done in Photoshop to make final decisions is a lousy way to approach a project, A process that includes prototypes could be much better.

What process do you prefer while working on your UI?