They are also the most impressive, but if you are going for something like Elementary Education or something like that, it's not worth paying the money to go an Ivy League school.
Well the top school changes from year to year but the top ten usually is the same ten year after year. They are California Institute of Technology, Harvard, Yale, Stanford, Princeton, Mass. Institute of Technology, UPenn, Duke, Dartmouth, U of Chicago. Right now it is princeton, last year I think it was Harvard the Year before that it was Cal Tech but in general the top 10 schools are the same each year. Also The Air Force Academy, Naval Academy and West Point are considered to be top 10 schools based on admission standards but they are not measured by the US News and world report, but I have had friends go their and said the education is just a tough if not tougher than the Ivy's, also a perk is it is free. Depending on what you want to do might help you out, If you want to do something like Engineering or computers based you might want to look towards cal tech or MIT even though all of them have good programs. If you are looking more towards business and the arts the Ivy's would probably be a better fit for you. Good Luck.
Harvard and Yale are usually considered the top two universities in the US, but if you're interested in the sciences or technology then something like MIT or CalTech is the best in the US.