I am used to travel 10 times yearly in plenty of European countries, Hungary specially, and I have been renting cars years ago.
Definetelly, Sixt are the Rent Cars Company with the best service, cars and support.
Their competitors are far away of Sixt efficiency, easy renting, no waiting in the offices and good support of the employees. Clearly, they have Customer oriented approach.
I highly recomend Sixt as the Rent Company Car to be choosen.