I agree that 500K isn’t going to get you what you want in UC. Could be worth waiting the extra year or two it takes to save a larger down-payment, though.
To answer the original Q, I would take PQ over Carlsbad due to the traffic on I-5. I’m just not a fan of NC-coastal and I would assume you might get a little more space inland as well, though I haven’t actually shopped them.