I think AVIS is pretty good. When you go, make sure to rent a new car (they might not have old ones anyway). New cars are in good condition, comfortable to drive, and most importantly, the navigation is very accurate. Unlike domestic navigation where you need to input specific addresses to find locations accurately, in foreign countries you can usually find places by entering the address directly. Finally, remember to buy full insurance. I had a minor accident while rushing back, but because I had full insurance, the AVIS inspector just asked me to hand over the keys and I was good to go.