Breakdown of Turntable Performance

I would say its the table, then the arm, and finally the cartridge.  The cartridge I think affects the color of the music the most, but you will not get there for some cartridges without a decent turntable and arm setup.

This is like the "which organ is the most important in the body" question. The a..hole almost won. 😀

Any views on Yamaha PX2, Yamaha PX3, Technics SL-M3, Aiwa PL-3000 ?. 

I have all of them. I like Aiwa PL-3000 . It can scan any track in any order. Very rare turntable.

As said somewhere above, the function of the motor and platter is to rotate the record at a constant rate, inaudibly. Other "contributions" (e.g., resonance) from platter, motor, and plinth could be viewed as defects rather than assets so ideally should be zero. The same is true of turntable support.  Once that is accomplished the rest is up to the tonearm and cartridge, correct compliance matching, and setup.  And of course the condition of the record.