Who should i priotize here?

So exams are in a couple of months including an oral maths exam which we have to do in groups but we dont get to pick them. Instead we have to send a ‘wishlist’ of people we wanna be with and its ranked too. Problem is i dont know who to pick. I wanna pick my crush as number one as i know she will actually do stuff and prepare + we have pretty good chemistry and i know she will actually try. Or i could pick my friend, who still tries but not as hard and we dont have that good chemistry. Problem is, i kinda promised the guy i would pick him as my number one. So do i keep my promise or not? Ofc the one i dont make priority number one will be the second and he wont know who i picked as first and second.