We have a plethora of Default voices available, and you will find an even larger number of voices available to you via the Voice Library.
One thing to keep in mind is that all Default voices and voices generated using Voice Design are English. This means that if you plan on using these voices for languages other than English, they might have a slight English accent. Unfortunately, there is currently no way to change this.
The way to get a voice with a proper accent for the language you want the AI to speak is to clone a voice speaking the language with the proper accent.
We also have professional voice clones available in the Voice Library under the professional category, indicated by the golden check mark. Theses are cloned voices of real people. You can use the language search filter to look for voices cloned in specific languages.