1 Turntable - nothing further down the chain can fix any speed and resonance issues here. In fact they'll only make them more obvious.
2 Arm - once again structural/resonance issues will make the job of the cartridge much much more difficult.
3 Phono Stage - very few amps have good phono stages built in. Some don't have any.
4 Cartridge - even a budget AT cart can give you very good results in a decent deck.
Besides they will wear out fairly quickly, are far too easily damaged, and are often a pain in the butt to change over and align properly.
It goes without saying that turntable siting is also very crucial if you want to make life easier for your turntable.
A lower performance turntable optimally sited will more than match a better one that is not in the same way a budget Ford will run better on a new road than a Tesla on a bumpy one.
The quantum world that turntables operate in is not readily visible to the naked eye or one that can be felt by human touch.