Multi-fam real estate vs Stocks for 20 years?

[David Schiman]

If you had the opportunity to buy a building for $850,000 at 50% down versus putting the same amount of money into the stock market and just letting it ride (assume VTSAX as the vehicle) which would you choose? And why?
More details:
I've got the opportunity to buy a multifamily building for $850,000.
Rents will be $9,300/mo first year, $10,500 second year (two units need to be finished)
$100,000 buildout construction loan built into mortgage
Commercial mortgage at 9% first year and 7.5% interest permanent loan, amortized for 20 years with a 5 year balloon. It's in Philadelphia and I am assuming a 5% appreciation rate and 1.5% yearly rent increase.