Both are good answers. Here is how to choose.
The structural question first
Real slate weighs 800–1,500 lbs per square. Synthetic slate (DaVinci, Brava) weighs 200–300. If your Evanston home was originally built for asphalt or shake — true for most homes built after 1925 — adding real slate requires structural reinforcement that can run $15,000–$40,000 on its own. Synthetic slate does not.
If your home was originally built for slate (true for many Lakeshore Tudors and a meaningful percentage of pre-1925 Victorians), the structure is already there. The decision becomes purely aesthetic and economic.
Lifespan
Real slate lasts 100+ years. Synthetic slate carries 50-year warranties and is expected to outperform — but no synthetic has been in service long enough to truly verify. Both will outlast almost every other choice.
Cost on a typical 2,200 sq ft Evanston home
Real slate: $55,000 to $120,000 installed, plus possible structural reinforcement. Synthetic slate: $32,000 to $55,000 installed. Designer-laminate asphalt that reads as slate: $19,500 to $28,500.
The curb appeal honest comparison
At 30 feet (the typical street view distance), high-end synthetic slate is genuinely indistinguishable from real slate to almost everyone. At 6 feet (the front porch), real slate's stone grain reveals itself in ways synthetic cannot quite match. Most homeowners choose synthetic and never look back. Some choose real slate because they wanted to and they could.
Resale value
In the Lakeshore Historic District, a real slate roof is a documented value-add at sale. Outside that district, the value differential between real slate and synthetic slate at resale is much smaller than the cost differential during installation. Choose for the years you will live in the house, not for the eventual sale.