I live/work here and we use a company called Vanrell, they send someone to meet you at the meeting point to give you your keys/contract/ take you to the car. Not sure how they compare price wise but always seem reasonable to me.
As I said, Argus were really good. Our car literally only had delivery miles on it.
They send a rep to meet you at the meeting point in arrivals where you sign the contract and he will take you to the car. I think they only leave enough petrol for you to reach the petrol station but its not bad as its right outside the airport.
Hope you have a great time. I still havent booked anything because of the cost (3 dcs means we need something pretty big) and I'm due to fly out on 18th July.