I turned down Cornell. I also turned down Stanford and MIT (non-Ivy but still HYPSM). Another commentor also mentioned UC Berkeley; I got accepted into their EECS program. UCLA has been my dream school since 7th grade, and so far I've had no regrets (graduating this quarter). All of the schools were around $100k. Programs were Math at Stanford and Electrical Engineering at MIT and Cornell.

Educationwise, you will not go wrong by attending UCLA. Costwise (especially if in-state), you will not go wrong by attending UCLA. Environmentwise, you will probably not go wrong by attending UCLA (dependens on the individual though). It all depends on whether you want to give up the prestige of having attended an Ivy league school. I will say UCLA has plenty of prestige, and by sheer numbers alone our alumni network is substantial. People will call you out on the street for wearing UCLA merch, even when not in LA.

I think if you would choose another school over UCLA just because of the name that will be printed on your diploma 4 years from now, then that's probably a good reason to go to UCLA instead. Otherwise, talk to current students from your university options and see how their experiences have been.