ElevenReader is pretty good:
https://elevenreader.io. It was free when it first came out (soft launch), then once it gained traction, they added a paid tier and limited the free features. This caused quite an uproar because people were used to unlimited use for free.
I haven't tried Readify, but it looks pretty new. Given what ElevenReader did, I wouldn't be surprised if it doesn't stay free forever. Just something to consider.
There are lots of horror stories on Reddit about Speechify not letting you cancel a subscription.
All that said, if there's a human-narrated audiobook, that is always my first choice. I only use TTS for books that have no human-narrated audiobook.