Your debate with your dad is hypothetical until you get admitted to a prestigious school. Are you a junior? Once you have some actual test scores, you can begin coming up with a list of possible reaches, matches, and safeties.
Even now though, if you want to continue the debate with your dad, how about going to the websites of example colleges in each category and calculating the net price for your family using each college’s Net Price Calculator. Prestige schools might not require as many loans as your dad thinks and can sometimes be less expensive than public options. Or, perhaps looking closer at what schools happen to hold the prestige for your prospective major will show that the options are different than you and your dad assume.
I suggest having test scores and looking at NPCs to flesh out your debate some more. Putting actual numbers on the expected family contribution, different types of loans, possible grants and scholarships, can help build a much more accurate picture. (Some NPCs include possible merit, for which you’d need test scores. RPI comes to mind as one well-regarded engineering school that does so.)
The choice isn’t necessarily binary, between 70k Prestige School and 30k No Name School; there are lots of schools in between, possibly less-expensive ones with great reputations and more expensive ones with less-good reputations for engineering. And then there are some big merit schools like Alabama Huntsville that can add to your debate.