Yes, CC to UC transfers get priority over CSU to UC transfers. Since the articulation agreements through assist.org are targeted for CC transfers, it is a much straightforward pathway than CSU to UC. Deciding to not go to SDSU is your decision but since UCSD does not offer TAG, there is no guarantee that you will be accepted to UCSD. What is your backup plan just in case?
Do you qualify for the UCSD University Link program? UniversityLink