cosign is better than guarantor.

Guarantor only guarantee the rent. 

Co-signer is liable for rent, damages, fines etc. 

Guarantor is liable for rent only after tenant won't pay.  You might wait a few days or weeks, after exhausted all negotiation with tenant, before reaching out to guarantor.  

Co-signer is liable for rent at the same time as tenant,  the rent is due on the tenant AND the co-signer. 

However, you can only sue anyone in their own state. So if co-signer or guarantor lives in another state, it's difficult to seek back rent.    As long as the co-signer and guarantor live in the same state, don't need to be in the same county, you can sue them in local county court.