SVT-AV1 is the fastest multithreaded AV1 encoder
You can download up to date BtbN ffmpeg build with latest STV-AV1 code.
Aom-av1 is the official av1 decoder/encoder but it's the slowest and lacks of a real massive multithreading.
Rav1e is a xiph encoder project. It's also very slow but you can use multithreading with tiles.
Dav1d is a veryfast AV1 VLC decoder project.
Svt-av1 is an heavy multithreading intel decoder and encoder. It produce good quality but bigger file size.
It can produce 8 and 10 bit video with CRF (default), CQP, VBR and CBR (test).
Two pass are also available with standalone SvtAv1EncApp but not in ffmpeg.