Turntable versus tonearm versus cartridge: which is MOST important?

I'm in the camp that the cartridge and the tonearm be at or near the same level. Tip either one too far and it's not a good match. On the other hand the table should be as good as you can afford. 

Many of us have had the experience where a medium or a budget priced cartridge sounds excellent on a very expensive turntable with a high-quality tonearm. I am among those who have had this experience. Therefore I would say the tonearm and turntable are most important. Which is really to say that you can’t get the most out of an expensive cartridge using a cheap tonearm and turntable. I guess I am more comfortable with that way of putting it.

I have heard and believe an excellent table/plinth is the building block for a good turntable.

Effectively the cartridge's job is to measure vibrations so the better the table and the tonearm the easier the job is for the cartridge to get the information.

Some people like car analogies - race tires and good seat and harness keep the driver in position enable a great driver to get more out of a car.  If the driver's not skilled then the impact of race tires and properly seating position don't really have an impact.