I’d like to know your thoughts on the strengths and weaknesses of each drive system.
Direct drive is direct. With an accurate enough clocking system, fast enough correction system, and a motor with a fast enough torque response, direct drive can maintain much higher speed accuracy than any of the others. The problem is all in what constitutes "enough". A good example if you want to get some idea of that is to read up on the Onkk Cue.
The weakness of direct drive is the challenge of dealing with vibration issues and motor smoothness (cogging) all of which are solvable, the question being at what cost. This is the one everyone leaves out, when in fact its the one that matters most. Its almost a complete waste of time to talk about the strengths and weaknesses while leaving cost out. Why do you think so many tables use acrylic and aluminum, and so many speakers use MDF? It ain’t because of their strengths and weaknesses. Its because they are cheap!
All the others, idler wheel, belt drive, are all trying to do the same thing. A belt is great for isolating motor vibrations from the platter. But it does that by stretching, which introduces speed variation, which is bad. Also the main reason for using belt drive is it lets you get away with a noisier motor that vibrates more. Well then the motor needs some kind of suspension to keep it from vibrating the plinth. And round and round you go playing with elastomers trying to get the right mix of vibration control with speed stability. All because its cheaper this way than building a proper motor.
Idler wheel is merely a variation on a belt. A variation that adds a bearing. Its crap, which is why it was so common early on and so rare nowadays.
The one you left out is rim drive, which is of course the best most cost effective solution, as why else would I have chosen it? https://systems.audiogon.com/systems/8367
Okay technically Chris Brady chose it. But technically technically it was a collaborative project of advanced audiophiles a sort of co-op called Teres Audio. So there.
In truth no one can say any one of these is the best, because this is a case of implementation being more important than technology. That’s why there are plenty of examples of great tables that use all these designs. That’s why once again the tech just ain’t all that and what counts is not can you figure out which tech is best but can you listen and hear which one sounds the best.