Just used Goldcar, which are out next to BK, ie minibus trip.
Plus Points:
Almost new car, we doubled the mileage (or kilometrage?) in our 11 days.
Price
Negative Points:
Slow service on both pick-up and drop-off, at the counter.
Buy full/return empty (in 11 days we did 3/4 of a tank)
€600 deposit, even if you have taken insurance through your broker. (Any damage will be charged, then you claim back through the broker insurance).
No AMEX, deposit has to be on a card of the main driver (I believe only credit cards, debit cards not accepted).
If the above doesn't bother you then they are a good choice, a few years ago I would have been happy with them, but now with 2 young kids I would pay more and go for the easier/better service.
Will say it wasn't just us having problems, when I arrived the other 3 groups there were in various stages of arguments with the staff, who seem to accept that their role is as a buffer between customers and management. Can imagine in high season very long wait times.