The firm analysed Zoopla data on average property prices and monthly rents to compare gross rental yields across UK cities.
Sunderland ranked first, with an average property price of £84,924 and monthly rent of £659, producing an average gross yield of 9.3%.
Aberdeen followed with an average yield of 8.3%, based on an average property price of £106,170 and monthly rent of £734.
Burnley completed the top three with an average yield of 8.2%. The average property price in the town was £92,473, alongside monthly rent of £634.
The analysis also found a concentration of higher yielding locations across northern England and Scotland, with Dundee, Middlesbrough, Hull, Glasgow, Liverpool and Newcastle among the top 10.
At a regional level, the North East recorded an average yield of 7.9%, while Scotland also stood at 7.9%. The North West ranked third.
Saif Derzi, property advisor at Landlord Resource, said: "There’s lots of information out there when it comes to picking the right location for a buy-to-let property, and it can be overwhelming knowing who to trust. Before basing your buying preferences on a yield figure, you should cross-check at least two independent sources - this could include a housing portal and a lending tracker.
"While the latest data suggests that buy-to-let opportunity in the North is great for a return on investment, it will cost you growth as a result. Typically, housing prices in Southern England have risen nearly twice as fast in the past decade as compared with northern counterparts.
"For those looking to pick an area imminently, they should note that city-level rankings are too coarse to buy on. You need to be honing in on exact locations, and the yield gaps between different city locations and local areas can be extreme."
