Just a quick reminder, make sure to have headphones/cans to monitor your audio.
Do I need them?
When recording they are not necessary, some voice actors swear by them and others say that they will hinder your performance. So you will need to determine if you like wearing them when recording, not having them on at all or meeting in the middle with them halfway on.
I like to use them, especially for video game and animation voice acting. It allows me to make sure I am staying consistent with a character, hear if I have mouth noise or some other weird noise happens and even if there is any sound leakage from outside the booth tainting my audio. It also make editing easier, since the headphones are already on, I can do a playback quickly and even do a punch and roll edit.
The reason some voice talent do not like to wear them is because it can distract you from your performance; hearing all of the extra noise that the microphone picks up can be a hindrance. They prefer to talk/act without anything else in the "way".
Either preference is fine.
The real purpose of using cans is to hear the playback and to edit your audio. I recommend headphones that have drivers and are neutral so that you can hear the full spectrum of the audio and that is not boosted in the highs, mids, or lows. If there is white noise in your recording, it is good to catch it before sending off to your client, than to have them find it — more professional as the former.
Do you have a recommendation?
I have only used one pair of studio headphones, the AudioTechnica ATH-m40x and I love them! It is suggested to get closed back cans to help block out any unwanted sound from outside.
There is the slightly cheaper AudioTechnica ATH-m30x, which is barely much different besides design and the output. From what I understand these would be great for voice over as well.
However, there are many different headphones to choose from!