Which SCORES to submit???

Hello, I am applying to highly competitive bioengineering/chemical engineering programs at UIUC (#1 choice), Purdue, Minnesota. I am also applying to BS/MD programs (Northwestern, Case Western, UIC GPPA). The schools generally do not REQUIRE essay, but given that they are highly competitive, I am worried my low score on the essay might make me lose my edge over other applicants.

Basically, I have the following choice:

Submit my higher SAT score with a WORSE essay score
OR
Submit my lower ACT score (especially SCIENCE is lower which is important) with a BETTER essay score

ACT: 35
-English: 36
-Math: 35
-Reading: 35
-Science: 33

-WRITING 11/10/11/11

SAT: 1570
-Math: 790
-English: 780
-WRITING 6/5/7

If it is relevant, I have three letters of recommendation: math teacher, physics teacher, French teacher. All are fairly good, though I suspect math/French will be the best.

Thank you, any advice would be greatly appreciated. I am a bit worried as I need to send the scores soon: deadline is Nov 1 for many of these programs.