DeepSpeech : simpler although inferior
Kaldi : STT supports hybrid NN-HMM and lattice-free MMI models. Kaldi is used by many people both in research and in production.
Lingvo is the open source version of Google speech recognition toolkit, with support mostly for end-to-end models.
ESPNet is good and well known for end-to-end models as well.
Wav2Letter, the tool by Facebook.
snakers4/silero-models at mlnews Silero Speech to Text
Tools and then