If your not happy with any of the currently avialable engines, and you have some developer time to spend, a research project may suit you well. This is not plug and play. These projects require patience and effort but they can be modified to your needs.
Kyubyong Tacotron https://github.com/Kyubyong/tacotron
Keithito Tacotron https://github.com/keithito/tacotron
If you don't care to much about quality and/or your TTS system has to work offline you can choose these options.
Cloud based solutions are an easy way to get high quality voices, but at a cost.