Kane is one of the best strikers in the Premier League and has been in stunning form for Tottenham Hotspur over the past three seasons.
The 24-year-old England international has won the Golden Boot for the past two seasons and could become the top scorer in the Premier League once again this campaign.
Lukaku is also a proven goalscorer in the Premier League and made the move from Everton to Manchester United in the summer transfer window.
The 24-year-old Belgium international striker has scored five goals and provided one assist in five league appearances for the Red Devils so far this season.
Former Newcastle United manager Souness, who now works as a pundit for Sky Sports, has stated that he would pick Lukaku over Kane.
“I said it on television last season and I’m sticking to it,” Souness wrote in The Times. “If you pushed me to choose between Harry Kane and Romelu Lukaku, I’d take the Belgium international.
“I can’t separate them on skill, so my preference is based on style. Kane is a fabulous player, with a great football brain and technique.
“He’s maybe more accomplished overall, but I reckon he sees himself as a part No 9 and part No 10, whereas Lukaku is an outright No 9, a centre-forward. They are rare today, the hardest thing to find in football.”
United have picked up 13 points from five Premier League matches so far this season, while Spurs have bagged eight points from five league games.