Turntable versus tonearm versus cartridge: which is MOST important?

If you ask someone involved in turntable manufacturing or sales, they will say turntables are the most important.

If you ask someone involved in tonearm manufacturing or sales, they will say tonearms are the most important.

If you ask someone involved in cartridge manufacturing or sales, they will say cartridges are the most important.   

In reality, they are all important.  

In the end, the firing squad would be a kindness.

A mercy killing. https://youtu.be/H59iOnYAsY0?t=24

We can make evaluations based on relative $ costs, but again the OP didn’t make it clear whether $ costs differences should be considered.  The OP still hasn’t clarified what his point is, what is he trying to achieve, or is just curiosity question without any benefit.

above all is synergy. tt and whole system. 

sometimes 'super and expensive " does not equal to better. but that's just me. 

expensive stuff need more care and level of quality of whole system. for instance. there is much more than just the cart, tonearm and tt

The Cartridge>Tonearm>TT or however the configuration of the items is assembled are in my mind not able to one item set aside as having the most importance. In terms of replaying a Vinyl LP it is this trinity configuration that proves to be the most successful method.
Each item is this trinity are totally dependent on each other and each item success within this trinity is dependent on critical tolerances for the designs of mechanics and critical dimensions for the geometric interface between the items in this trinity.
All parts will need to interface within the very well known geometric parameters and each part will need to function to the accurate designed mechanical operation.
If a item can not interface within the trinity that caters for the meeting the critical mechanical function and geometric interface, then in my mind it is only then that the item will fall from being of importance within the assembly.
There are Various Brands, Various Purchase Values and Numerous Ancillaries on offer of Items to produce the trinity.
If the designs from these producers are capable to achieve the above then the ideal set up can be achieved at a variety of budgets.