SDSU transfer admission rate is less than 20% - akin to UCLA. Unlike UCLA, their mission requires them to make room for ‘local’ applicants. That, simply doesn’t leave many seats for out of area students like you A sub 3.4 will make you noncompetitive, especially for Engineering majors.
It looks like Davis has a lower TAG threshold - assuming you meet their 3.3 bogey, you should definitely apply via TAG.
http://admissions.ucdavis.edu/admission/transfers/trfr_stmr_ce.cfm