So, I haven't read this thread thoroughly, but quickly one thing about the thread, followed by a brief explanation of what I've been told (both my parents graduated from the USAFA academy)
1) Whether or not the academies are rigorous/easy to get into:
I mean, it's fairly difficult. Or atleast, it's higher than average. But their is certain to be a mix of both. My mother was valedictorian in her fairly large high school and went to the air force academy. My father was top of the batch too. They were elite students, and they went. But they were also professors at the USAFA after they finished the Air Force payed for their graduate education- from what they've said, a lot of the education of the academy is really just the effort. They'd give problem sets (chemistry and physics respectively) that were large parts of the grade- remember, at the academies, you must go to class all the time. So, the professors will actually be aware of anybody who is struggling and failing- and would actually try to help those who are legitimately trying.
So, it's not just a collection of jocks or morons. It has a full spectrum of people. But most are intelligent, or if not intelligent, they're determined and work hard.
Now for 2) Is it worth it?
Answer (from what I've been told): only if you actually care about getting high up in the military ranks. Is an academy education better for the military? Not necessarily. But for better or for worse, that shiny little "academy" degree will help with promotions and everything.
The academy is a trade off- remember, that civilians will make a lot more money than the high up military officers, for the same level of work. But if you want to get high up in the military, for service or whatever the hell you want, then go ahead.
Some trade offs-
1) be kept busy all the time, and have to do a bunch of crap. You'll have to wake up and march around, and have no free time. For no reason often. They'll just decide to arbitrarily make you do stuff during the day. You have to put up with this for 4 years. And they'll yell at you. For no reason.
2) Not really gain much of a benefit in reality. You can get the same stuff from ROTC, but with a lot more free time. And a normal college life.
It's basically 4 years of no free time. And being told to do random stuff- with no benefit. And the benefits you do get you can get elsewhere.
Now, I have no idea how the army/navy works. But from what my parents say, unless you're really set on a military academy, or I guess if you need the free education (academies are free), then it's not really worth it. But they were also non-combat, and the air force did pay for their graduate degrees.
Unless you plan on being in the military 20+ years, and there really isn't any possible way an 18 year old can say that when they've been alive for only 18 years, then ROTC is better. Atleast if you can get any $$ out of ROTC.