Sometimes the answer is one of ours, and that is worth saying on a page like this.
Pick a featured voice when the video is not about you. A product walkthrough, a how-to, a training module, anything a stranger could narrate and nobody would blink. Featured voices are open on every plan, including Free, and you can hear the featured voices before you pick one. Free starts you with 8,400 credits, once, which is enough to hear what one of them does with your script.
Clone your own voice when your name or your face is on the thing. Your updates, your ads, your client videos, anything where someone who knows you is going to hear it. A stock read does not cover that, and people notice.
Both of them are text to speech underneath. You type, a voice reads. The only question is whose voice it is, and text to speech for video is the same job without the camera.
The price of speaking is the same either way, 3 credits per second of audio. What differs is the set-up: cloning your own voice is on every plan, Free included, and the first set-up is included on every plan.