How does ULID compare to Instagram's bigint id_generator for postgres?[0]

ULID is 128 bits vs 64 bits for instagram id, so ULID is stored in a uuidfield but instagram id can be stored in bigint field.

There is some advantages of using the application code to generate the ID though (avoiding roundtrip to DB if need to use the ID afterwards), but I'm seduced by just offloading this work to the DB and being able to use bigint field to store the id.

As someone who is just about to commit to using ULID or an instagram-like bigint id generator, would you have any thoughts you could share on which may be better?

[0] https://instagram-engineering.com/sharding-ids-at-instagram-...