depending upon how much knowledge you have on using one depends on what to go for, if your knowledge is minimal i would suggest going for a DA as they're a lot more forgiving. a rotary polisher isn't.
regarding polishing your car to bring a shine back, need to ensure you have no contaminants on the surface so prior to polishing you want to use a fall out remover and clay bar the car too.
MY DA is from Rupees and my rotary is a bluepoint one. both been faultless but coming up 10 year old now, there may be better on the market.