I can't speak much for our MechE program, but I do know a number of MechE students here, and I know that at times it can require a lot of work, just as CS and ECE do, which is potentially somewhat of an indicator as to how good the program is.

I do have some advice for your application, though. When you apply, assuming you are still pretty unsure about what degree you want to end up with, list CS as your first preference. If you are a CS student here, transferring into CIT(our engineering college) is easy. However, you need to prove you can do OK in CS before you can transfer into it, which forces an uncertainty period after deciding you want to transfer. Also, if you list CS as your second choice, and you get into your first choice, then they will tell you that they didn't consider your application since you have already been accepted to another college and they have limited slots. Also, you seem to group CE and CS together, and while it's true they do that at some other schools, here you must at least take the basic classes in EE for an ECE degree. So, if you end up not liking EE, and you are in the ECE program, you are going to end up taking unpleasant classes that you wouldn't have had to take in CS. If you are majoring in CS and you end up not liking programming or you find it to be too difficult, you can transfer into CIT with relative ease and major in ECE or MechE.

Another note, yes we are probably more "diverse" than MIT, but their ECE and CS programs are just as good as ours, and their MechE program as ranked as the best, so I'm not sure what type of diversity you are looking for. You mention Cal, so I assume you are OK with living on the west coast, however you don't mention Stanford. Stanford has similar rankings, and arguably a better atmosphere/location. That isn't to say that MIT or Stanford are better schools, only that you shouldn't eliminate that unless you are sure. I would recommend applying to every school you consider a serious possibility, and then visiting them after being accepted to help decide. If money isn't an issue, you can visit as many possibilities as possible before you apply to limit your applications. You will probably get comments telling you we are simply the best and you should choose us over everyone else, but every person is different and I think you should try to get as good an idea as you can of what it is like at the schools before deciding.

This probably doesn't help you much in your comparison of our MechE program with other schools, but I wish you well with your decision, and I hope you end up here if the fit is right.