UIUC is probably the better option if you can afford it, and you get accepted directly to CS. CS is super competitive at UIUC. Additionally, Computer Science and Stats is different from majoring in Computer Science (which is in engineering at UIUC). If you do not get directly admitted to CS at UIUC, it is probably better to go to Purdue rather than taking the high risk of transferring into CS at UIUC.