UCSD and UCSB computer science chances

My son was accepted as undeclared at both UCSD and UCSB. He really wants to study computer science and has heard that getting into CS in these two schools is very difficult. Do you recommend one over the other for chances?
He also was accepted directly into CS at Santa Clara and Oregon State. Would those be good options if the UC schools are impossible for CS?
Thanks for any advice you have!

UCSD is by lottery once you pass the screening courses. UCSB is also tough due to very few spots that open up due attrition. If he really wants CS, have him go for the direct admit since neither UC is a guarantee.

UCSD:
UC San Diego students who wish to change from another major into one of CSE’s capped majors may apply to the Department of Computer Science and Engineering for admission into the BA computer science, BS computer science, BS computer engineering, or BS computer science with specialization in bioinformatics major.

Eligibility requirements:

Minimum of eight units of courses completed at UC San Diego for a letter grade, drawn from the following screening courses: CSE 8B or CSE 11, CSE 12, CSE 15L, CSE 20, CSE 21, CSE 30, and CSE 100.
All of the following eligibility courses (or their accepted equivalent) must have been completed prior to application: CSE 8B or 11, CSE 12, CSE 15L, and CSE 20.
Students must receive a 3.3 GPA in screening courses taken at UC San Diego.
Application process:

Students may apply in any quarter after they have completed the above eligibility requirements. Students who meet the 3.3 GPA cutoff for screening courses will be entered into a lottery. Students will be randomly selected until the open number of seats in CSE are filled.

UCSB:
Changing Your Major or Double-Majoring With Computer Science (UCSB students only)
Severely limited resources and our desire to provide the Computer Science (CS) majors with an excellent education and learning experiences has made the CS change-of-major process extremely competitive.

The following are the minimum requirements for consideration. Every student who meets these requirements will be admitted, as of the 2017-2018 school year (subject to change in future years due to demand). Transfer students admitted under another major are not eligible. NO EXCEPTIONS MADE FOR THE FOLLOWING REQUIREMENTS.

Complete the following requirements:

A cumulative GPA of at least 3.0
Satisfactory completion of Computer Science 16 and 24 with a cumulative GPA of 3.2 or higher; First takes only.
Satisfactory completion of Math 3A (or 2A), 3B (or 2B), 4A, 4B and Computer Science 40 with a cumulative GPA of 3.0 or higher; First takes only.
In addition, students are required to have

Never been placed on academic probation,
Fewer than 105 total UCSB units (AP/IB or other transfer units do not count towards this total)
A study plan submitted with the petition demonstrating the CS degree can be completed without exceeding 200 units or five total years of post-secondary study, including time enrolled at other institutions.
Students should submit their petitions to the Computer Science Department before Week 6 of the quarter they are finishing the requirements. This will ensure a smooth transition into the next quarter of classes provided the petition is approved. The change-of-major petition and study plan can be found here or picked up from the CS Department office in 2104 Harold Frank Hall. The department will respond to petitions when the quarter is over and grades have been submitted. Any denied petitions will not be reconsidered due to the no exception policies stated above. For additional questions, contact the CS Undergraduate Advisor Margaret Salisbury.