If both boats were in the same condition, and had the same equipment, I might be inclined toward the Islander.
Sounds like the Catalina's ready to go, though. Another consideration for a novice might be that the Catalina 30, and Catalinas in general have a very strong association on Lake Michigan. Lots of friendly, helpful people. Many of them with the 30 footer. They also have a wealth of printed information relevant to the 30. They're always looking for new members.