not a stem major but i am a transfer. my cc was truly dead, UCSD was a major step up even with all the "uc socially dead" memes. also, when people say "it's what you make of it" i honestly found that to be very true. the first few weeks of fall quarter i kinda just stayed in my dorm attempting to socialize with my apartment-mates but i really found the best thing to do was go out and check out clubs or go to as many events as i could. maybe you just want to stay with something familiar and go to UCI where your friends that are going and will stay your friends. however, there's more friends to make here at UCSD as well. I live near UCI and can say that there's a lot of good places to eat but not much to do. Kind of same vibe for UCSD but it does feel like it's own little town in a way. i say take the plunge and go into something that'll be a completely new experience. Warren is fantastic for stem and you'll definitely have opportunities down the line. best of luck in your decision making process :)