I have a 3 flat in Lincoln Park, Chicago, IL that I am planning to list for sale in the next 3-6 months.Currently owner occupied in 1 unit (Duplex up, 3 bed 3 bath).The other 2 units (2 bed 1 bath each) are rented.I am wondering if it is more attractive to buyers to leave the 3 bed 3 bath unit vacant when I move out, or should I place a tenant in there and then list for sale?

At the top of your screen you will find a section called "Build your Team" There, you can connect with property managers, realtors, lenders, and CPAs that specialize in real estate, and you will find Cincinnati well represented with highly reviewed professionals, by members of BiggerPockets, who are eager to compete for your business. 

Deegan and @Arda Bircan There are technically 7 Tests for Material Participation (but 3 that are most common) -> the individual 500 hour mark, that the activity of the individual is substantially all, and that the individual participates more than 100 hours + no-one else spends more time than them.Litmus Test: Are your hours integral to the operationsThe hours that qualify must be substantially all hours and have a legitimate impact on the rental activities.Activities that generally count: showing the property for rent, taking tenant applications & screening tenants, preparing & negotiating leases, cleaning & preparing the units for rent, repairs, and improvements, managing the construction, purchasing supplies & materials, inspecting the property, responding to tenant complaints & inquiries, collecting & depositing rents, evicting tenants, writing & placing advertisements, and working on your websiteActivities that don't count: education & research, investor-type activities, and travel time..

One that helps lease creations, screening (background checks, etc), and possibly even the advertising on different platforms like compass. 

Street sweeping And probably a few more I am not thinking about.Dig out and utls are lump sum.foundation lump sum  he pays for the concrete.Framer supplies his own nails fasteners and installs the windows.roofer supply's all materials.insulation supplies all materaislPlumber supplies all materialsElectrician supplies all materialsPainter supplies all materialsFence supplies all materials flat work supplies all materials.counter tops flooring tile work are all one sub they supply all materials and one price. thats off the top of my head. 

Look into their marketing efforts, tenant screening processes, and response times.Service Audit: Conduct an audit of the services provided by Ace Management and Reality to ensure they are actively marketing your properties and maintaining tenant relations effectively.4.

In Israel, I would also need to pay 15% on my income (a flat rate), which would still be around 5%.Tax report in israel cost around 300$, I assume it is about 500-600$ in the USA or less and its a one time fee / year.

Don't let things like that go unchallenged or you may find yourself in a pickle down the road.Biggerpockets sells a Lease Agreement Package under "TOOLS" at the top of your screen. $100 for a lease and several other documents, written by investors and attorney approved for your state.

And you ran an eviction screen on them with no records found. 

I have screen shots, emails and receipts where I can prove everything I'm saying.