I need to use a MacBook Pro compatible , 3rd party app to create synthetic voices (American accents; female late 20's; female early 50's; male late 50's) for Movie. Can the Apple community make suggestions?

Apple's Consumer Apps Department told me that I should only add these voices after I have finished writing it in Keynote. Afterwards, I then hit FILE (in the drop down options), "Export to" and then "Movie". Some 3rd party apps options for these synthetic voices are:

Murf

Resemble.ai

Voicemod (in App store)

Speaky

NaturalReader (in App store)

Lovo.ai

Synthesia

I would appreciate any comments on the above or for an other third-party apps that can create synthetic, American-accented, voices.