I have been using VoiceFlow. It works incredibly well and uses Groq to transcribe using the Whisper V3 Turbo model. You can also use it in an offline scenario with an on-device model, but I am mostly connected to the internet whenever I am transcribing.

Check out the FUTO keyboard or FUTO voice input apps. It only uses the whisper models though so far.

Does the Android keyboard transcription not work for your needs?