AI Voice Library Recommendations

I will be gaining access to the paid AI Articulate 360 suite in mid-June of this year. I'm in the process of storyboarding web-based courses that will be developed in storyline and disseminated to a broad global organization. Because English will not be the first language for most learners, the neutrality and clarity of the AI voice chosen is very important. 

Can the community recommend voices (male and female) that are middle-aged, neutral in accent, and very clear to a broad global audience? American accent is preferred, with a focus on the mid-west/Illinois being most neutral. Thanks!