Keep it simple, stupid.

I’d use the built-in dataclass (or something even simpler) where possible. Only when I need more functionalities (e.g. validation) would I switch to using Pydantic model.

Depends on what you are trying to accomplish, pydantic is great for encoding/decoding

If you don’t need that go with dataclasses

For validation and/or (de)serialization: pydantic.

Otherwise, dataclasses.

I also like to replace tuples with NamedTuple, but I tend to use tuples a lot in the first place. It’s generally recommended to use dataclasses instead if you don’t specifically need tuple-like behavior.