Harvard and Caltech.
I completely disagree.
Caltech may be in the top ten engineering schools but certainly
not top five...while Harvard is not even in the top ten.
The best answer is Stanford and UC Berkeley.
That depends how you interpret "rival". From a ranking/academic
perspective, you may be right (though I feel Caltech is comparable
to MIT). From a personal/historic perspective, MIT has a long
history of hacking with Caltech and Harvard (MIT stole the caltech
cannon!). In the MIT student culture, Caltech and Harvard are
ingrained as the main rivals.