UCI or UW?

So, I got 2 offers in my hands so far, one from UCI for computer engineering major, and another one from UW with pre-science major. Which one is the better choice?

Which UW?

If Washington, then getting into the CSE major is highly competitive:
https://www.cs.washington.edu/academics/ugrad/admissions/regular
https://www.engr.washington.edu/admission/department/admitstats (ignore the non-CSE major stuff, since they changed how other engineering admissions is done starting this year; since you are not Direct to College of Engineering, it will be harder for you to get into a non-CSE engineering major than listed there)

If you are in-state for California, UCI is the obvious choice, since you are in what is presumably your desired major and it should be less expensive. If you are in-state for Washington, you have to weigh the uncertainty of getting into your major there versus the lower in-state cost. If you out-of-state for both, UCI is more expensive by about $10,000 per year, and you have to decide how that trades off with getting into your major.

I got accepted by UW Seattle, and I in neither California or Washington. I am not taking tuition into consideration right now. Which is the better choice academic wise?

Why not? Neither will give you any funding. They are public schools.
Both schools are strong schools.

UCI because you were a direct admit to your desired major.