Do you wish Alexa would respond to your commands with different voices? You'll get your wish soon. Amazon has released a developer preview that lets Alexa skill developers use a selection of voices from Polly (Amazon's text-to-speech service). An adventure story can give each character a different voice, for instance. Creators could already 'hack' additional voices in through MP3 recordings and similar techniques, but this is decidedly more elegant.
The feature currently only allows using eight US English voices (Polly supports roughly two dozen languages), and it should take a while before multi-voice skills arrive. However, the timing couldn't be much better. Google just added six voices to Assistant. While this clearly isn't the same (many skills will just use whatever regional voice you have), it should lead both to some basic variety and voice apps that are considerably more complex.