Congratulations on getting into both schools!!
Where do you want to be located long-term? SMU is great for the DFW area, and UCI is great for Southern California. It will be more difficult, but probably not impossible, to get to Southern California from SMU and vice versa.
Based on your post, I assume you want to stay in electronic engineering, or something similar. I don't know much about hiring in DFW except that there are definitely jobs there, but the Irvine area has more hi-tech/engineering jobs than you could ask for. Yes, USC and UCLA are nearby too (UC Davis recruits more into San Francisco, which is pretty far from Irvine); UC San Diego is relatively close by as well. However, the Irvine area is an up-and-coming Silicon Valley of sorts -- many many tech companies are in the area, including Google, Oracle, Kingston, etc etc. Hyundai (if you want to focus in electronic engineering in the auto industry) also has its headquarters nearby -- and they do recruit from UCI.
Hope that helps! Sorry this is more of a one-sided post, but you'll have great options no matter where you go.