Other metrics include property-appreciation rates and the average number of days it takes to lease a vacant rental.
The trade group also says Utah's relatively low property tax rates and annual homeowners insurance premiums let rental owners keep more of what they earn from their properties than investors in other parts of the country.
The study says Western states in general rank better for returns on rental investing than other regions, accounting for seven of the list's 10 best U.S. rental markets. Among other Western cities with high returns are Seattle, Portland, San Francisco, San Jose and Denver.
Salt Lake City's ranking is part of a well-documented surge in rental markets here and across the U.S., driven by demographic trends including a large generation of young, frequently cash-strapped adults choosing for now to rent instead of buy.
With homeownership rates approaching their lowest levels in a generation and rents rising, All Property Management says, "it's a wonderful time to own rental housing."
That news won't surprise investors in Utah's rapidly expanding stock of apartments as new complexes rise across the Salt Lake Valley and surrounding counties. But if you're a renter or looking for an apartment, some of the trends might give you pause.
With vacancy rates down, average monthly apartment rents jumped 4.9 percent in Salt Lake County in 2013 and 2014, ending last year at $892 per unit. That's according to a January 2015 report from Equimark, a Salt Lake City firm that tracks multifamily residential real estate along the Wasatch Front. More recent numbers, circulated by the commercial real estate firm Berkadia, put average rents in the wider metropolitan area at $933 a month as of March.