If it is to be any Canary Island, sense would be TFS but it wouldn't surprise me if any of the four became a base.
The islands have this unique ability to have year round sun and very high air fares compared to the rest of Europe.
Just take a look at some of the fares the so-called 'low fares' airlines are able to charge, some over £400 one way (not mentioning any northern airline in particular) yet their aircraft got out and come home packed to the rafters, not to mention the money they make onboard!
If not Ryanair, easyJet will be there before long...