Cadera Medina is possibly the best but you need to book in advance - we went down to get a car on the day and there were none available. Went up to Plus Car and the price advertised was €20 but she told us it would be €40 - when I queried she couldn't tell me why it was double other than it was to do with 'I don't know why my boss does that'. We went up to Auto Borges, and had the most straightforward car hire experience ever - yes he had a car, €30 for the day (no extras - price quoted was what we paid) and the whole transaction completed within 5 minutes with no problems. Really nice guy to deal with, speaks several languages so you won't have a problem with communication, and the cars are spotless and comfy. Would hire from here without hesitation when we go back.