Milwaukee reserve time is shorter at the moment. Somewhere between 1-3 months. Reserve time in Chicago is longer because most commuters can get there easier and it's simply a larger base.

Schedules in Chicago have pretty much every variation under the sun. Milwaukee is almost exclusively early starts and late ends. First plane out of maintenance is a 6a departure. That means be at the airport at 5:15a. Then there's a 7:15 & 8:30a. The last planes to come back to MKE typically don't land there until 8:30, 9:30, & 10:30p. Your 3-4 day schedule in Milwaukee will always start and end with one of those flights.

Somewhere during your days, you have a 20ish hour overnight where you swap from the early morning shift to the afternoon/evening shift. Most folks would like to stay on the same shift given the choice (1st shift start early/end early or 2nd shift start late/end late). The longer overnight and swap to 2nd shift causes some to complain about the schedule.

If you live in between, give MKE a try. You will get off reserve faster and probably be offered an upgrade faster. Lots of people don't want MKE for a lot of reasons. Mostly commuting and schedules. If you are willing to put up with the inconvenient schedule, the rewards might be a little higher.