It depends in so many factors, such as how many records you will have, if you need to be able to work offline, and so on. I have an App (private) that shared a large number of records using CloudKit and a local cache with coredata. Now I'm dividing that App in multiple Apps and I thing I will use a mix between full synchronize tables and cache tables, all sharing the same record zone. I would recommend that you start using only CloudKit, then you can start adding coredata for cache, if you realize that you need it.

Just a comment, I have had much more than 5000 records in a single CKRecord shared for many many years without many problems, so I think that limit is no longer valid.