I assume that none of you are US students. I'm an American student who applied to and got offer from unis acroos the pond, such as LSE, UCL and KCL. I also applied to Oxford but was cut after the interview.
A few things:
1. I'm really frustrated by the preocupation with Harvard. Harvard is an incredible university, but it is crucial to remember that its reputation comes from its graduate programs, and not for undergrad. Undergrad at Harvard is actually said to be the worst of all the Ivies, because Harvard professors have very little concern for their undergraduates. They're top researchers in their fields, and there are a million other things they'd rather be doing than wasting their time with undergrads. Harvard is still a good school, and the academic environment (being around genii) is definitely a positive. Did I apply to Harvard? Yes, partly out of curiosity and also because of parental pressure; however it's still near the bottom of my list. I just think you should make an educated decision.
2. I truly do not see the advantage in getting a bachelor's degree from a US uni over one from a UK uni, unless you plan to live and work in the US. All the schools you named, except for Reed, Oberlin and Wesleyan, are of a similarly high caliber for American schools. LSE is in that same caliber of schools, arguably even better then more than a few of those schools. Grad school is another matter, but for undergrad there are loads of advantages to LSE vs. US schools. LSE is 3 years of specialized study ina premier social science uni, and the US option is one more year at double the cost at least (plus they force you to spend the first 2 years unrelated to your major).
Sorry for the novel, but I just felt like you needed a more balanced perspective of this entire thing.