Ratiometric vs Regulated Sensor Output
A ratiometric sensor's output is irrelevant if you don't consider the power supply voltage that feeds it therefore, such devices as RTDs can use a pull-up resistor to form a potential divider and an ADC uses the supply to the pull-up resistor as its reference - that is a ratiometeric method of obtaining the value of the RTD.

If you are just wanting to transmit an analogue value down some simple cable to something that reads it then you can't really use a ratiometric method because you don't have a measurement of the excitation voltage on the device. This is why on remote strain gauge bridges sense wires are used to ensure that cable volt drop is factored into the measurment i.e. the terminal excitation voltage across the device is remotely held constant.

If you have a sensor that provides a fixed voltage (or current) output irrespective of the supply voltage (such as an AD590) then you are forced away from the simple ratiometric measurment method and (if using an ADC) you have to have a fairly precise reference voltage by which you make comparisons.


  If i had an option should i choose regulated 0-5v output sensor and
  what is advantage of that?


Go simple first and try ratiometric. If this can't deliver the accuracy then a different sensor might be needed or a different method of communications between sensor and receiver.


  Do i need to use amplifier?


Not always