you really need to give more detail: what time of year, do you want to be near a beach, is it Tenerife only or all the Canaries, or anywhere warm (which is a huge area).
Very broadly speaking, why not get a brochure from someone like Thomsons, have a look for anything you like and then check it out against the reviews on TripAdvisor? (Don't pay too much attention to the very best or very worst reviews, just get a general idea of what facilities it offers and whether people have enjoyed themselves.)