@theloniusmonk, science is also part of STEM.
In terms of undergrads sent on to S&E PhDs, U of I and UMich are about the same (U of I is strong is various sciences as well). I agree on the rest.
So purely in terms of ROI, if you stay in engineering (or science), it’s hard to justify paying up for UMich and if you do, it’s for a luxury good (possibly more pleasing campus atmosphere). Better opportunities at UMich if you leave STEM.