A very good question, without a simple answer, despite what you might have read or been told.
This question comes up a lot and there are many technical considerations. Technically, direct-drive has advantages, specifically in terms of torque and drive speed consistency. It’s much cheaper to make a belt-drive turntable though, this is why affordable decks tend to use belt-drive. It suits small manufacturers who can basically build a belt-drive turntable using a $5 motor.
It’s much more expensive to design and build a direct-drive machine, especially a really good one. The performance advantages of direct-drive systems explain why some of the best and most expensive turntables, tape machines and lathes from the most advanced manufacturers use direct-drive.
Most of the records you listen to were recorded and mastered on direct-drive tape machines and cutting lathes. Ever wondered why that is? If belt-drive was superior, wouldn’t it be used instead, where cost is no option? Of course. This is why great direct-drive machines are highly sought after, but there are some spectacular, highly desirable belt-drive machines too.