So I've been a cheerleader for USC as of lately and thought it'd be helpful to share my thought process in becoming one.
You're right that USC hasn't had the best performance in recent years. Their career center lost its leader and its only now showing the progress of its new head from Stern.
That said, on paper Marshall isn't where it used to be. However it only has one direction to go. The university as a whole is a HUGE success story. It has made more traction than any other school university-wide in establishing itself and there is no doubt that this a name that will only continue to grow in prestige. The SC name is respected in LA and if you're looking into tech, it carries its weight. I worked closely with recruitment at Google and can attest to the fact that hiring is very California centered as it is what recruiters are familiar with. USC has a good rep in the start up scene as much of their hiring is predicated and how well you click with a company's culture. They want people who are fun and easy to work with and free of the ego's some MBA's assume their degrees entitle them to.
Emory isn't a name I encountered often in tech and I can't remember any MBA's from the program in either of the divisions I worked in. That isn't to say Emory grads aren't competitive (it's a great program on the rise!) however you're right in that it loves placing in the South (where no doubt it reigns supreme). Plus I wouldn't doubt our office in the South are stacked with them.
If you're familiar with people in the start up scene or at the names you had mentioned, you'll find SC grads abundant at any of these places. Couple that with the Trojan network and you should be in pretty great shape. Marshall grads are pretty diverse in their pursuits and I felt better about my internship and career prospects from USC than I did at programs like LA where the competition within the class was more than I would have liked. Much of tech is about who you know as there's no shortage of well educated people searching for tech jobs in California. It's easy to hop around when you have a network like USC to rely upon.
I'm professionally familiar with Atlanta and know what the name Emory means in the South. Unfortunately it doesn't translate over to the West Coast as accurately as it should. You could say the same about USC vice versa.
So at the end of the day, if you can handle a small difference in rankings (and one I think won't last too long), USC makes a lot of sense.
Do what feels as right after visiting as they're both great programs. 16K isn't huge but might be worth mentioning to SC (they have a HUGE endowment). Did Emory have its admit events yet? I will be at USC's in 2 weeks!
Best of luck!