Sabonis in my eyes, is one level above anyone, including Doncic.
Take a look at Jokic and picture someone twice as good at least. Sabonis did everything Jokic does, only better + he could defend. He was the first Center in the world that was point center. When he came to the NBA, it was towards the end of his career and his knees were done...
Kukoc was amazing, winning titles left in right both in Europe and in the NBA. But, he wasn't the type of player that can carry a team to NBA title on his back. Dirk, Luka, Sabonis - absolutely could (and Dirk did).
Very hard to judge Luka, because we factor in his age, that's what makes him so amazing and unique and he will have to continue to improve and so on. He was 16 years old only when he started to play for Real Madrid (one of the most titled teams in Europe). He was one of the stars (with Llull) in Real that won Euroleague in 2018 (he was 19 years only) and one of the stars of Slovenian NT when they won Eurobasket in 2017 (he was only 18 years old). I can't remember any player at such a young age, doing half the stuff he did.