Depending on who you ask, you will get different answers on which lens is the best for portraits. Some will answer with zoom lenses, typically with 24-70mm or 70-200mm focal lengths, and then there are the prime lens users with their 85mm or 135mm lenses. Here is another lens you probably never thought of using for portraits.
The lenses I mentioned above are not the only options, and really any lens can be used depending on the look you want. It depends on what you are trying to achieve. I have been using my Canon 35mm f/2.0 lens a bit more recently to do some more environmental portraits, but I haven't tried using a tilt-shift lens for portraits yet. In Eric Floberg's latest video, he talks about how he uses the Canon TS-E 45mm f/2.8 tilt-shift lens along with his Canon 5D Mark IV. After discussing how the lens performs and how it affects your images, Floberg shows some examples of his work while using the tilt-shift lens and follows up with a demonstration on how it can affect your portraits.
Breaking out and using different lenses in your work can help you get creative and capture unique photos. Sure, you can achieve similar effects in Photoshop, but capturing these effects in-camera also looks better in my opinion. As Floberg states, it forces him to be more creative during the shoot. What are some other unique lenses you use for portraits that are not typically used?