I've had the chocolate souffles at Michael and at La Sardine, and both are excellent. It's been a long time since I dined at Les Nomades.
Since these are three very different places, here are differences to consider:
Michael is in north suburban Winnetka, about twenty miles north of the Loop. If you don't wish to drive, it's only a block from the Indian Hill station on the Metra UP North line (and what 11-year-old doesn't love a train ride?). The food is creative French with global influences. It's mid-priced among these three choices, with a three-course prix fixe for $50. Elegant, but not overly formal (jackets NOT required, but blue jeans not appropriate).
La Sardine is in the West Loop, just west of the Loop. The food is traditional French bistro fare. It's the least expensive of these three options, with entrees around $20. Casual (blue jeans okay). They have a special on Tuesdays, any three courses for $27.50.
Les Nomades is a fine-dining restaurant in Streeterville, just off the Mag Mile. The food is very creative French with global influences. It's the most expensive of this group, with a four-course prix fixe for $115. Elegant and formal (jackets required for gentlemen).
Just as a FYI, souffles are very easy to make at home, even for novice cooks. I know they've gotten a bad rap on television because it's easy to joke about them falling at the slightest touch, but that's overblown (no pun intended). Follow a good recipe and it's not terribly hard at all to have one come out well. Most recipes have you create a foil collar around the edge so they can rise over the top lip of the souffle dish, but I usually make it easier on myself by using a larger souffle dish than specified, thereby not having to deal with a collar. The only difference in the results is that you don't get the visual effect.