What's the best route through Chicago from Madison?

I have to go to South Bend, Ind., from Madison, Wis., this Wednesday, so I'll be going through Chicago during the dreaded rush hour. I can take 90 from Rockford to 290 and then 294 to 80. Or I can take 39 south to 88 to 355 to 80. I'd like to leave the house by 8 a.m.; I need to get to South Bend by 2 p.m. so I'll have to leave no later than 9. Will traffic through Chicago be better if I wait til 9? And which route will be better? Thanks!