Are more turntable motors better?

yes, probably too much rubber from inferior quality can decrease sound quality. To minimize the contact area will help =)
To move it away from the platter via more motors has a lot of advantages, more money for the manufacturer and better sound.
But with a better belt ($100) you can save a lot of money (honestly, the most).
Or with a better motor.
But you need for everything a good and important explanation.
But please, not from an engineer =)

A point not yet mentioned is that the typical belt drive solution suffers from inherent belt creep which causes loss of dynamics and accuracy. (The key word being "typical") Mark Kelly has outlined this at various places on the Internet. You will find the appropriate math along with those explanations. There are workarounds to reduce belt creep however, and a three motor implementation is one approach. There are at least three other clever approaches to the problem that I have seen that connect the belt in various ways, add components, etc. It is a given that belt condition matters, and although it is an important aspect, it is not the only primary concern.

http://db.audioasylum.com/cgi/m.mpl?forum=vinyl&n=694199&highlight=belt+creep

*Disclaimer...I manufacture turntables that do not use belts. I mention it, not because anything I have said here is controversial, but so it won't appear that I am attempting to promote any agenda.

One direct drive motor is better.

"One direct drive motor is better."
It can be better than some other individual designs, depending on the implementation. Then again, it may present yet another set of problems. For example, if the direct drive motor uses a correction loop, an analog sort of jitter can be detected. That may cause a noticeable lack of dynamics, or even smearing, in some setups. Another example would be that if a motor is used that is too noisy or weak, the result wouldn't be optimum. My belief is that any drive type has certain caveats when carelessly implemented. A turntable, like your system, is a whole entity that is as strong as its weakest part. The drive can be near perfection, but if all the other aspects of the build are not properly addressed, the end result isn't the best it could be.

I will say that when I added the Micro Seiki HS-80 passive flywheel to my (obviously single-motor) thread-driven RX-5000, the background was as quiet as ever, but the solidity of piano notes was even more impressive. A clever solution to keeping it simple yet providing even more system inertia.