I would choose Owen over Marshall 100 times out of 100, and I would choose Nashville over LA 100 times out of 100.
HOWEVER, I was not an international student who would've benefited (potentially a lot) from the STEM aspect. Also, I was not dead-set on pursuing Tech, even though that's where I ended up. So you're in a different spot than I was... I think you can make an argument for either option here.
BTW, beyond just the strict ROI and job placement, it is worth also considering that these programs will be very different. USC has a different vibe than Vandy, and LA is totally different from Nashville.
Are you more interested in a small, friendly, Southern community feel (albeit in the midsts of booming Nashville), or are you the more cosmopolitan type that really needs/loves the diversity and options available in a metropolis like LA? I would also consider that.
Good luck with your decision!