Kane has managed 99 goals in 165 first-team appearances for Tottenham, including 29 in the Premier League last season as he topped the scoring charts in England's leading division.
Lukaku, meanwhile, netted 25 Premier League goals last term, and the Belgian has scored 71 times over the last three years at Everton.
Chelsea have been strongly linked with a move for Lukaku in this summer's transfer window, but Cundy has claimed that his former club should be pursuing Kane, who is also a better option than Real Madrid's Cristiano Ronaldo, according to the 47-year-old.
Cundy told talkSPORT: "If you are giving me the option to buy either one of those players, I'd take Kane every single day of the week over Lukaku. I would rather Harry Kane over Cristiano Ronaldo, too.
"All-round, the value he's going to bring, because of what he can do, the player he's going to turn into. I have faith in my judgement. Harry Kane is twice the player Lukaku is - based on my eyes, based on my knowledge, based on what I see.
"He's twice the player, Kane is twice the player. Harry Kane is a better player, he can hold the ball up with his back to goal and Lukaku can't. However you dress it up, the better player is Harry Kane."
Cundy represented Chelsea between 1988 and 1992, before turning out for Tottenham.