Zaha penned an extension to his contract at Selhurst Park, keeping him at Palace until 2023.
He was linked with big money moves to the likes of Tottenham, but nothing materialised. And former Liverpool player Souness is a huge fan.
"I think he's sensational," Souness told Sky Sports.
"I can see him playing for Real Madrid, that's how good he is. I think there's maybe a handful of players who have got the change of direction and balance that he does, and I think he should get more penalties, he isn't a diver.
"I think he's got a unique talent and with the utmost respect to Crystal Palace - and maybe he's been scarred by the experience at Manchester United - he's ready for a big, big club, the biggest clubs.
"If he stays at Palace he's going to end up with no trophies and think, 'What if'.
"I think now he's ready. Even for the big two in Spain, I think both of them would welcome him with open arms, he's a door opener, and there isn't too many of those players around.
"He's unique in our football. He's in that league, he's got the stuff that gets you on the edge of your seat."