UCSD is one of the top programs in systems and networking, period. Starting from the mid 2000’s, they’ve built up a powerhouse in their center for networking and systems, with real superstars like Amin Vahdat, Stefan Savage, Geoff Voelker. These are the very best in the field, period, and you can see by the ridiculous list of pubs they have every year at the top conferences in networking (SIGCOMM, NSDI), security (oakland, usenixsecurity, CCS, NDSS), systems (OSDI, SOSP), and even the occasional data mining (KDD) or HCI conference. Even though they’ve suffered some attrition in the last few years (Amin is now leading data centers at Google, and George Varghese left for MSFT), they are still the program to beat. They did hire George Porter, who’s excellent and another young star in the making. IMO, UCSD is easily on par with the best in systems/networking departments, MIT, Berkeley, UW.
UCLA has been higher ranked for decades, but they’ve been struggling a bit lately. They still have stars in networking, but most are fairly senior faculty (Songwu Lu, Lixia Zhang, Len Kleinrock). They hired a young systems star in Eddie Kohler, but couldn’t keep him (he left for Harvard a few years later).
I’m sure I’m more biased towards these people because I’ve known many of them through going to the same conferences (SIGCOMM, NSDI, UsenixSecurity etc), and also because there are many connections between UW, UCSD, and UCBerkeley where I did my PhD. I’m happy to call many of the UCSD folks my friends and mentors.
As for TAMU, I know some folks there. Dmitri Loguinov is very good, but he’s on the more theoretical side of networking, i.e. analysis papers in INFOCOM. Guifei is very good, but he’s security, so not quite networking/systems as you asked. I know Dilma from many years ago while she was at IBM Research. It’s a nice group, but I would easily pick UCSD out of any of these choices without hesitation. Heck, if I were to go back for a second PhD, having already gotten one from Berkeley, I’d go bug UCSD to see if Stefan or Geoff would take me in their lab 
PS: there are no other factors I can see that are really relevant. SD and LA are both cities, as it Dallas, but none are startup powerhouses like Silicon Valley. SD and LA are both close enough to get some benefits, and SD has Qualcomm (and every networking/systems company under the sun interacts with CNS and pays a fee for the privilege). So even on the metric of industry interactions, UCSD wins.