Crete Car Hire - Anyone to avoid

[omniflow]

Looking to rent a car in Crete - I would like to book it now(ish). Prices look pretty good - approx £650 for just over 3 weeks. All the companies I've looked at appear to offer "full insurance", which looks like it does what it say on the tin - i.e. zero excess. This should then eliminate any issues with being charged for pre-existing damage. However, I am slightly wary of this.

Companies I am looking at are:

CarHellas
Cretecars
Rentcar.gr

All come in at roughly the same price and all have fairly similar Ts & Cs. Are any of the above to be avoided, or does anyone have any recommendations of specific companies? I would like the car delivered to our Hotel in Chania and then I'd like to drop it off in Heraklion at the Airport.