For car hire best thing to do is find the best deal you can then post details (dates, airport, size & best price you find) then if anyone sees a better deal they will let you know.
My last trip was with Expedia/Hertz (price error £197 for 25 nights)
Next weeks trip is with Holiday Autos/Dollar got great price in their Jan sale.
August Best I have seen so far is USrentacar/Dollar but paid an extra £10 so I can cancel and book elsewhere if a better deal comes up.
No one company is best, they all have offers & errors from time to time