Wow, this is a massively subjective question, one that could generate responses all over the board, especially if bias enters the equation...
In my mind, this is difficult to answer, as I'm not sure what your career goals are. I also have no idea what it means, "CSUN because it's government."
If your goal is to get a job at a major accounting firm, say, one of the Big-4 (say, for your audit experience, as well as having it be a springboard for the rest of your career), then the first thing I would consider is (1) how many of such firms recruit out of the school in question and (2) how many people were actually hired for the past few years out of such school.
As Kirby correctly noted, cost is an enormous consideration. Cal State universities often (always?) have the advantage of being significantly cheaper than Universities of California & that's something to consider.
My general advice, and it's been this way for years now, is that I recommend that if you can find a Cal State school that kicks ass in your major (in this case, accounting), I'd likely go in that direction first, instead of the more expensive UC option.
Why?
Because all you really care about is just getting your foot in the door (e.g. getting a job). The accounting firms aren't going to say, "Well, you went to school at "X," so I'm going to pay you more..." I can assure you that your first year at a major accounting firm, you are all equally worthless.
I've seen the exchanges though and they've been pretty funny: "How much did you pay to go to school (i.e. USC)? And you got the same job I did, making the same money????
Sucker!!"
But, this is not to say that going to, in this case, USC is a terrible option. First of all, USC has one of the best business programs in the state and (last I left off) all major firms recruit out of there, so you can rest assured that you're close to maximizing your chances of finding a job post graduation.
Further, USC is very popular (if you went out of state) and well known across the U.S. and some believe that USC graduates tend to get the benefit of the doubt when evaluated by USC alumni. Granted, once you get a job, especially if you've worked for X number of years, that tends to dwarf whatever college you went to, but it is something...
IF you can get past the cost hurdle, there is little question I'd choose USC.
But it's a VERY significant hurdle to consider. In my mind, unless CSUN has really taken a dump in its business/accounting program (which I don't think it has), I would go there, as that's a Cal State school that kicks ass in accounting. I think most of the major accounting firms recruit heavily out of there, so I think your chances of landing a quality job are fairly high (all other things equal, of course). And, once you get ~ the same job, you'll be happy you didn't spend all the additional $$.
One thing to note: Please do NOT be buffaloed into thinking that just because someone went to school X that they are smart. I've had the unfortunate experience of running into people that couldn't find their ass with a map, but think that just because they went to school X they were smart...UGH...I can assure you, that isn't reality
