There has been a tremendous amount of discussion on Quora about this already. Note, that Wikipedia has defaulted to the terminology of Speech synthesis, instead of TTS. For that matter, Wikipedia contains a Comparison of speech synthesizers. BTW, Nickolay Shmyrev is a good person to follow on Quora for speech technology answers.
See also my quick and dirty webpages:
· 100 Best Speech Synthesis Videos | Meta-Guide.com
· 100 Best Speech Synthesizer Videos | Meta-Guide.com
· 100 Best Text-To-Speech Tutorial Videos | Meta-Guide.com