Really? How come they survived 2 years of TS, then?
Look how happy Zoro was meeting Luffy again back in Sabaody & Wano, and then compared it to his muted reaction at meeting the Cook again on both islands.
Zoro and Cook tolerate each other. That's it. They know what the other is capable of doing, but any notion that they are friends is laughable, if not outright trolling.
And saying they are best friends is like saying Don Krieg is stronger than Akainu.