Car Hire Lisbon Airport

I wonder would anyone have any information on car hire in Lisbon Airport,
I am going there in 2 weeks time for 10 days .Is it cheaper to book a car when I get there ,or book on line in advance and if so does anyone know of any Car Hire Companies based there that give good value as there seems to be a huge variance in price for the same car using different sites.
Thanks

Book online in advance is normally the best deal (no matter where you are going.)

In Europe I find that the best deals are always to be had using aggregators like Auto Europe, Holiday Autos, Argus Car Hire etc. rather than directly with the car hire companies Avis, Hertz etc. (No matter which channel you book through the actual car will come from one of the big rental companies)

(By contrast in the US you can often get as good or better deals booking directly with the hire companies in my experience)

All the major car hire companies will be represented at Lisbon Airport.

I used www.economycarrentals.com a few weeks ago. Booked on internet.Picked up in Lisbon. No insurance excess. Excellent service.

Thank you both for your help .