xTTS is not open source but you can download it and use it for some things - and it's the nicest sounding one.

Bark has potential but the voice quality is pretty off.

The tortoise fork which improves the model and restores cloning (the author of tortoise decided it was to dangerous and crippled the project) is ok with some voices but it takes a lot of tries.

Voicebox from Meta is pretty good, comparable quality to ElevenLabs, but it's research-only for now.

Pretty sad overall.