Here's some info I pulled together a couple years ago:
Harbor-UCLA: Smaller cohort of 10 residents per year. No free-standing children's hospital. Suffers from the typical resource limitations of a county hospital, with residents doing a lot of scut work. Located in an OK but less than desirable area of LA. Not being a Spanish speaker might be somewhat limiting. Not all electives can be done at Harbor, but since they are affiliated with UCLA, there haven't been problems with completing them. Inpatient ward at Harbor is older (it's a county facility), but peds ED and outpatient clinic are newer. On the upside, it's a very busy hospital that serves a large uninsured population: working here is an incredible experience and truly reflects a career in medicine as one of service to those in need. Solid training, nice level of autonomy, and extremely diverse in terms of ethnicity / clinical exposure, though maybe a little limited in some specialties.
CHOC/UCI: Larger short of 27-30 residents per year. Large, beautiful free-standing children's hospital, lot of resources, very strong inpatient training, resident run program. Strong attendings / mentoring, and not too many fellows so reasonable degree of autonomy & procedures (though maybe not as much as at Harbor-UCLA). Known to be great for hospitalist training. Very diverse patient populations, strong culture and supportive leadership. Spanish might be an advantage here too. The hospital is located in a pretty desirable / nice area of Orange County, much nicer than Harbor-UCLA. Keep in mind that the location is not Irvine, it's about 15-20 minutes north in an older, more diverse town of Orange, CA. Plenty to do. Another point of mention, this program is a very busy, high volume, very heavy workload, inpatient heavy program, with only 3 months of dedicated outpatient training. Lastly, there is some driving involved as there is a 10-month component at Miller's Children's Hospital in Long Beach, CA (about 20-35 minutes away).
If it were me, all things considered, I'd probably choose CHOC.
