I wondered which UW until I read “Allen School”, which I take to mean that UW is the University of Washington.
UW is excellent for computer science (and this would be true regardless of whether “W” meant Washington, Wisconsin, or Waterloo). I do not think that you are gaining anything by switching to UCLA. Employers in California know how excellent all three of these particular UW’s are.
If you were in-state in California and UCLA were less expensive then I would consider switching. Given that UW is less expensive then I would stick with it.
I would expect that if you get accepted to a really top level graduate program (eg, Stanford level) then you will find that other students in the same graduate program come from a huge range of other universities, and that a LOT of the other students in the same graduate program, possibly a majority, come from undergraduate schools that are ranked a bit lower than any of UCLA, U.Washington, or the other two very strong UW’s.
These are significant plusses for UW. I would stick with it.
I might add that I worked for many, many years for a very good high tech company headquartered in California, and the company I worked for hires LOTS of people from out of state universities. U.Washington on your resume will get your foot in the door at companies in California.
You are in at two really excellent universities. Congratulations!!! However, I think that UW is the stronger choice here between two excellent schools.