I dislike geico, heard bad things about them being hard to work with on claims, I wouldn't want to wish that on anyone just to save a few bucks.
My brother was in the car rental industry. He always told me that if a customer was getting screwed by their insurance, over a policy that included rental coverage while their car was in the body shop, nine out of ten times it was a Geico customer.
I know a collision shop owner pretty well. He claims that, from his end, most insurers are competent and fair to work with, except Geico. When he gets a Geico customer in, he warns them that Geico has a history of not paying for 100% of the cost of doing the job correctly, and he may be looking to the customer to pay the balance. Typically he eats the loss, but sometimes he rolls the car out into the storage area, and waits for Geico to step up, and stop trying to screw him and their customer, before he continues a repair.