A good question, without a simple answer, despite what you might have heard.
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 be belt-driven. This suits small manufacturers who can build a belt-drive turntable using a readily available, low-cost 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 utilise direct-drive methods though.
Most of the records you listen to were recorded and mastered on direct-drive tape machines and cutting lathes. Ever wondered why that might be? The answer becomes obvious, if belt-drive was superior, it would be used, where cost is no option. This explains why many of the great turntables are direct-drive and why those machines are so highly sought after. It’s not what everyone wants to hear, but there’s no escaping the facts.
People get really angry about this, specifically, lovers of particular belt-drive brands, but there’s no need. This is simply about science rather than opinion and this can be hard for those who have an almost ‘religious’ belief in a brand or methodology because they are so heavily invested in it. The beauty of science is that it has no place for opinion, only facts.
There are some spectacular, highly desirable belt-drive machines, make no mistake and for all who think I hate belt drives, my current turntable reference IS a belt-drive, but it has a 10kg platter…!