In Salford, whose Media City (pictured) is occupied by the BBC and ITV, landlords made 7.08% in the year to March 2017.
Other strong performing cities are Leeds, (5.96%) Manchester (5.79%) and Coventry (5.64%).
Meanwhile the worst places to invest in terms of yield are Chelmsford (2.89%), Cambridge (3.17%) and York (3.17%).
Tarlochan Garcha, chief executive at Kuflink, said: “This index shows that savvy investors should look to the regions where strong rents and more affordable house prices make for fruitful investment opportunities.
“The Northern Powerhouse is leading the way, while London falls by the wayside, as rents fail to keep up with rocketing house prices.”
In London, Barking and Dagenham has the best rental yields (5.30%) followed by Newham (5.19%) and the City of London (4.58%).
The worst yields are in Southwark (3.82%) and Greenwich (3.93%).
Garcha added: “The stability of both house prices and rents is a positive sign for buy-to-let investors, proving the strength of the UK’s property market, which is able to withstand the uncertainty surrounding the UK’s exit from the EU.
“The following few months will be the true test of the market, as Article 50 negotiations get underway.”