You want a directory or a listing of the best
Unfortunately, you're out of luck. All of the so called directories with rankings are really nothing more than ads. The plastic surgeons that pay can get ranked at the top and participate, plus censor comments. The others (no matter how good they are) don't get many eyeballs.
The best way is to ask friends and family, that way you know their testimonials are authentic. Other than that, I believe your best bet is plastic surgery forums (like this one

) and other sources for personal reviews. But there are a lot of unethical doctors out there that manipulate opinions by posting themselves (just check the breast implant forum on here to see an example!) so remember that when reading reviews.
Unfortunately I do not know of any plastic surgeons in Milwaukee, or Wisconsin for that matter. Just keep up the research and let us know who's on your shortlist and we can give you our opinions