Thinking about doing a junior transfer

After being rejected from my top choices, I’m left with UCSB(comp sci), UCI(comp sci/engineering), and BU(college of engineering), each costing about ~17k. By no means are they bad schools, but I feel like my admissions results could have been much better if I took the time to actually educate myself and do some research on prospective choices. I rushed my college essays and did not take the college admission process seriously. I had a 3.87 u/w gpa before applying senior year and a 2220 sat score with decent EC’s. My question is what steps should I take in order to attempt a successful transfer for schools such as Penn/Cornell/Brown/etc, or if I should just try to succeed at the schools I’ve been admitted to and try to apply to these schools for grad school. Thanks for any replies.

Grad school.

Grad school.
BTW, any of the three for 17K is a bargain, but I’m surprised wrt BU.
Can you look at your financial aid package and list this here:
X University: (tuition, fees, room, board) - ( scholarships, grants) = $… (loans$…)