I got into both schools; ucsd outright and just came off the waitlist at ucla. The issue is ucsd is offering me a lot of financial aid in grants. I would be paying 6k+ more a year to go there than ucsd. I’m studying economics… the thing is I want to go to a top MBA school and I feel going to ucla for undergrad could offer that. Any thoughts? Is it worth the debt?
The time to draw up lists comparing the two schools was in the six months or so from when applications to transfer were due back in November. At this point you’re going to probably have to just go on a hunch
Top MBA schools do not admit students directly from undergrad, something from your question that you do not seem to realize. They expect several years of relevant work experience.
So the question really becomes one of the second order effects, which of these two schools is better for launching you into those type of jobs. This is a question with no solid answer because a lot more depends on you and what you do than the school. For example getting relevant internships is a real key, and that’s up to you. how well how will you interview is again a function of you and not the school. There may be differences in who recruits at each school, but it’s going to be a struggle to find out before you need to decide.
Academically, there is no wrong choice between the 2 I think you are over-valuing the halo effect of UCLA but, . It is certainly not worth $25k in incremental student loans when you earn your BA/BS.
Since you note you plan to go to grad school, pick the cheap one.
Both will offer similar leadership and internship opportunities - though probably in different industries. That (and GPA/GMAT) is where you set yourself apart from your classmates.
Internships will be much more important than which UC you choose. Go to ucsd, be excellent, get professional experience 
and you’ll find a good MBA program interested in you.
UCLA is not worth 6k more than ucsd for the academics. For the social life, well that’s up to you. MBA programs do not admit right out of undergrad. Get work experience then get one.
Go with UCSD.
As measured by faculty scholarship, UCSD appears to be strong in economics (as does the slightly lower placed UCLA):
https://ideas.repec.org/top/top.usecondept.html
I think the overall brand name recognition and prestige of UCLA wins out every time.
Plus, you’ll have a bunch of people saying (or thinking) “oh, yeah, San Diego State…party one dude”
meant “party on”