Is there any reasons to prefer BIGINT instead of UUID (other than the very few % of performance, which may never be a problem)?

I just find instagram's ID complex (custom epoch, mandatory use of RETURNING) while Ulid is elegant (easy to generate and use).

For me the biggest selling point was the interoperability with other kinds of UIDs, if later your requirements change.

Also, note that (at least in Rust) Ulid are implemented as u128, so are pretty fast.