Pro-Ject Prebox RS - no linear power supply (unless you buy the additional external linear power supply for more money). Potentiometer volume control.
rogue RP-1 - very good linear power supply with good capacitance bank. I’m going to assume it uses a resistor-ladder volume control. I also see a couple nice film/poly capacitors next to the tubes for better output audio quality. Pro-Ject does not have anything like this. It looks like all the op-amps are socketed, so it's possible you can try swapping out different op-amps for improved/changed sonic signature.
Schiit Freya - based on picture looks good. Based on feedback, it is an "okay" device.
In the end, you get what you pay for in most cases.