RHVoice is queued for analysis. Crawling candidates and ranking them takes a few minutes. This page updates itself when the list exists — you can also come back later.
What is known so far comes from the other direction:
These projects were analysed and named RHVoice among their alternatives. The relationship is not symmetric — how RHVoice rates them is a separate judgement, made when RHVoice is analysed in its own right.
calls RHVoice “choose it for a higher-quality Russian voice in a native C++ library, at the cost of far fewer languages.”
eSpeak NG is an open source speech synthesizer that supports more than hundred languages and accents.