<p>Selectivity and prestige are sometimes related, but a university is seldom prestigious because it is selective. Generally speaking, it is the other way. A prestigious university will be selective because it is in demand. Of course, a school like Michigan, with over 25,000 undergraduate students, is going to find it hard to be as selective as a smaller university like CMU, which has barely over 5,000 undergraduate students. </p>
<p>This said, CMU is not more prestigious than Michigan. In Engineering circles, all three schools you are considering are equally respected. As Vick mentioned CMU is considered best in all things Computer whereas Michigan and GT have a strong reputation accross the Engineering spectrum. However, in terms of overall prestige, Michigan is more prestigious than CMU or GT. That's thanks to its top ranked Business, Law and Medical schools, top ranked academics in almost every traditional academic discipline, as well as its huge presence on Wall Street, popular culture and in Silicon Valley. Michigan covers all aspects of humanity like only a very select few universities do.</p>
<p>Finally, a well-rounded experience means that you will enjoy it more. It means you will have more variety in your social life. Of course, if you intend on spending all your waking moments studying, and then, if you are 100% sure than you want to be a pure Engineer for the rest of your life, it does not matter. However, if you wish to experience more than just studying in college. If you wish to make friends, have fun from time to time, perhaps even take classes in an unrelated field just for the hell of it, then, a well-rounded university will help. Your friends at CMU and Georgia Tech will mostly be majoring in Egineering, the Sciences or Business. At Michigan, you can meet people majoring in almost every field of study. Furthermore, if you wish to cross-over from Engineering to another field, either when in college, upon graduation (when looking for a job), or later in life, a degree from a university like Michigan could help. Finally, and this may not matter to you since you don't seem to care about social aspects of college life, Michigan is 50% male, 50% female. CMU and Georgia Tech are more than 60% male and less than 40% female. That's another way in which Michigan is more "well rounded"! hehe!</p>