Which 1 of the 3 cell phone companies in spain
has the greatest network coverage. Ie which one produces the best signal strengh whether up a mountain or in Barrio.

They have a similar coverage. It depends on where specificly you want to go. The operator which has the nearest mobile station is the one which will have the best coverage.

I will try to avoid Amena, which was the last operator to enter the market, and thus, has slightly worse coverage.

Fernando

From what I have heard Telefonica has the best cellphone coverage, but it also depends on the model of your phone. I have Telefonica, but get very poor coverage in my office whereas some of my clients do get coverage with the same provider but because their model phone is better than mine.

I have Telefonica Movistar too. They and vodafone are the best for coverage. I think Telefonica has a little better signal in some places, based on comparisons with friends phones. I would stay away from Amena too.