I assume you’d be full pay at all three schools?
Between Rice and Northwestern, Rice has a lower sticker price (by about 10K I believe) and also a stronger CS reputation, so on objective measures it seems like a stronger choice. The residential college system is a huge plus, and the fact that Rice is very undergrad-focused is a plus too.
Evanston and Houston are very different places, though; and the schools have different personalities, so it depends what you prefer.
Rice also has particularly good flexibility to move between majors (more easily than at a UC) but not as much of an interdisciplinary bent as Northwestern (which makes a point of cultivating “CS+X” pursuits), if blending areas of interest is a desire.
How sure are you about CS in particular? Any particular focus within CS? What alternative majors would you consider if you changed your mind about CS?
Do you hope to come back to CA after you graduate, and just want a different experience for college, or are you trying to “launch” in a different region? It won’t matter so much in CS, because it’s relatively easy to be recruited across regions; in some other majors, it’s harder to get a job far away from the school. (My daughter who attended Rice spent three years working in Houston after graduation, which hadn’t been her plan or desire, but that’s where the job was! But she wasn’t a CS or engineering major.)
If you would like a smaller program with more individual attention within the UC system, consider the College for Creative Studies at UCSB. There’s an additional layer of competitive admissions for CCS. The Computing major is research-focused and allows you to specialize in an area of interest. https://ccs.ucsb.edu/majors/computing