Their side
When Google Docs voice typing is the right answer
If your writing happens in Google Docs and you write in English, use it. It is free, it is already in the Tools menu, and the voice commands for punctuation and formatting genuinely work. Installing a separate tool to dictate into a document that lives in Docs anyway is extra machinery for no gain.
It also wins in two specific places we cannot reach, both of them about the machine rather than the writing. Google Docs voice typing runs on Linux and on Chromebooks through the browser, where SnailText has no desktop app at all. And it works on a computer you do not own - a library machine, a colleague's laptop, a client's desk - because there is nothing to install and you just sign in.
Those two cases are where we would tell you not to buy SnailText. They are also narrow: if you write on your own Mac or Windows machine, in a language other than English, or anywhere outside Google Docs, neither applies and the comparison goes the other way.