A good photographer for engagement photos will have a unique methodology, knowledge of equipment and experience working with clients.
The best photographers know how to capture the moment in an artistic way so that you can look back on your photos and remember how you felt when you took the pictures.
You want to be able to trust your photographer so that you can relax and have fun during your session. A good photographer will make sure that they capture your personalities and love for each other through their pictures.
A professional photographer should also be able to help you choose locations for your engagement shoot that are scenic and interesting but also comfortable for both of you. The perfect location will depend on what type of photos you want and what kind of moods you want to convey in your photos.