The EASIEST and most RELIABLE device to get to talk is the IKEA Symfonisk $99 speaker. It is a pretty decent Sonos speaker under the IKEA labeling. This speaker works with Hubitat's built-in SONOS speaker integration and does a very good job at TTS.
The other two options you mentioned have some Pros and Cons to each.
The Google Home Mini can be used as a TTS device using Hubitat's BETA Chromecast Integration. While this works, it has some quarks. First, these devices often go unresponsive, requiring one to click the INITIALIZE button on the device details page within Hubitat. Second, this integration has been found to cause overall hub performance issues for some users. Since it's still classified as beta code, many, many months since its original release, I am personally not a fan.
Using an Amazon Echo device for TTS requires some custom community code. Choices here are @tonesto7's very full featured 'Echo Speaks' integration and my very simple 'Alexa TTS Manager' integration. Both integrations use the same behind-the-scenes technique to masquerade as a user logged into alexa.amazon.com within a web browser session. This is somewhat tricky since it requires a browser 'cookie' to be refreshed periodically to keep the user logged in. Take a look at both, if you're curious.
So, you have some options to consider. If you have any questions, feel free to ask.