Getting into Grainger is the most difficult of the options. That would be CS within the engineering school. We were told by an AO that has a 12% admit rate (2019). The CS+X programs are slightly less competitive, but not by very much.
BTW, USNWR has UIUC’s CS program at a tie with that of Princeton. That means CS at UIUC is no safety for anyone.
CS through Grainger is the only one that has the option/possibility to earn a 5-year masters.